问答题If you could invent something new，what product would you develop？Use specific details to explain why this invention is needed.

问答题《复合题被拆开情况》 HOW ANIMALS IN RAIN FORESTS MAKE THEMSELVES HEARD 1 Scientists have discovered that animals are experts at exploiting weather conditions and the physical conditions of their environments so

问答题《复合题被拆开情况》 HOW ANIMALS IN RAIN FORESTS MAKE THEMSELVES HEARD 1 Scientists have discovered that animals are experts at exploiting weather conditions and the physical conditions of their environments so

多选题What possible causes does the student consider for not liking the taste of vegetables? Choose 2 answers.

多选题What are the implications of the theory that bananas arrived in Africa 5,000 years ago? Choose on 2 answers.

多选题《复合题被拆开情况》 MESOLITHIC COMPLEXITY IN SCANDINAVIA 1The European Mesolithic roughly the period from 8000 B.C. to 2700 B.C. testifies to a continuity in human culture from the times of the Ice Age. [A] Th

多选题《复合题被拆开情况》 COMETS 1 Comets are among the most interesting and unpredictable bodies in the solar system. They are made of frozen gases water vapor, ammonia, methane, carbon dioxide, and carbon monoxide

填空题.Prions and Illness Prions are proteins responsible for several infectious diseases that can affect both humans and animals. In humans, prions cause a number of neurological diseases which result in a decrease in cognitive functions and that almost always end in death. Creutzfeldt-Jacob Disease—often called mad cow disease because of its debilitating effect on bovines—is one such prion disease that strikes the human brain. Some others are fatal familial insomnia, kuru, and Gerstmann-Straussler-Scheinker Disease (GSS). These diseases, while different, share some similarities, particularly their cause. Prion proteins are attached to cell surfaces and are usually not harmful; however, in each of the aforementioned diseases, a prion protein in the brain assumes a wrong shape, disrupting the cell it is attached to. This signals nearby prion proteins to form improper shapes, too. The process slowly spreads across the brain as it destroys neurons, builds up plaque-like matter, and makes holes in brain tissue. It is slow moving, so it may take several years before the first symptoms are recognized. There are three main forms of prion diseases: acquired, genetic, and sporadic. People get acquired prion diseases through infections by bad prions, typically through food. Kuru, a prion disease that was once common in New Guinea, was caused by cannibals eating the brains of people with bad prions, and Creutzfeldt-Jacob Disease, which humans get from ingesting infected beef, is another example. Genetic prion diseases are passed from parents to children through genes as an error causes the genes that code prion proteins to make mutant prion proteins that, as the children age, attach to cells in the wrong shapes. Fatal familial insomnia, which is found in a few families worldwide, causes people to be unable to sleep, and eventually leads to death, is one such example. As for sporadic prion diseases, they have no definitive causes. Experts believe they manifest because of mutant genes but are not certain why people acquire the diseases. Roughly 85% of prion diseases are sporadic as their victims are not exposed to infected food and have no family history of prion diseases. *bovine: an animal such as a cow or buffalo *neuron: a specialized cell that is a part of the nervous system

填空题. The Unsaturated and Saturated Zones The two primary divisions in the upper layers of the Earth are called the unsaturated and saturated zones. These two terms refer to the amount of water that each zone holds in addition to the ability of that water to move. Each zone has special characteristics that make the movement of water possible or not based primarily on the amount of soil and the types of rocks found in the ground. These zones do not have defined limits, their depths may vary considerably, and they are both vital for agriculture and for use as sources of fresh water for animals, plants, and people. The unsaturated zone is found in the upper level of the soil, where water may be confined in small spaces between particles of soil and rocks. Because of the greater amount of soil and rock compared to water, water has a difficult time moving through the unsaturated zone. It is more restrained and compressed than water located in the saturated zone beneath it. More solid rock, such as granite, permits water little movement while more porous rocks and soil, such as sand and clay, allow water greater movement. Nevertheless, despite the solidity of the unsaturated zone, water can still move through it by flowing both upward and downward. Rainwater seeps through it to the saturated zone while plant root systems draw water from this zone, which makes it a crucial component for plant survivability. The saturated zone lies beneath the unsaturated zone, and its upper level is commonly called the water table, in the saturated zone, water flows more freely because there is less solid rock to interfere with it. The depth of the saturated zone depends upon a variety of factors, including what type of rock and soil are underneath it, the amount of rainfall the area gets, the presence of nearby rivers and lakes, and the amount of water that is consumed by humans. Layers of solid bedrock beneath the saturated zone limit its depth while the presence of more porous rocks and soil causes it to be deeper. Heavy rainfall means that more water seeps into it and that water exists in greater concentrations. Rivers and lakes, however, tend to drain water from the saturated zone as some geologists estimate that up to thirty percent of the water in some rivers comes from the saturated zone. Finally, when humans dig wells to take water from the ground, the saturated zone gets depleted of water. The area between the unsaturated and saturated zones is a narrow region that has been termed the capillary fringe zone. In this place, which varies in thickness from a few centimeters to more than half a meter, the water in the saturated zone is drawn up by capillary action into the unsaturated zone. The distance the water moves upward depends upon the types of rocks and soil. If the rocks and soil there have large pores, only a small amount of water will be drawn up a relatively small distance. If the rocks and soil have smaller pores, however, more water will be drawn up, and it will travel a greater distance into the unsaturated zone. The reason is that capillary action works better in objects with smaller pores due to the properties of liquid surface tension, which is required for capillary action. The human usage of water from the saturated zone can have tremendous effects on the environment as taking too much water for both agriculture and human consumption can have disastrous results. In some places, the loss of water from the saturated zone causes the subsidence of the unsaturated zone, resulting in large depressions in the surface of the land. In other cases, overconsumption can cause the disruption of agriculture. For example, one of the largest saturated zones in the United States, the Ogallala Aquifer in the Midwest, has 170,000 wells pumping twenty trillion cubic meters of water to the surface annually. The result of this extraction has been an average drop in the depth of the water table of almost four meters in the past few decades, and there have been extreme drops of as much as sixty meters in some regions in Kansas. This has led to a decline in agriculture and an increase in the cost of pumping water up from the saturated zone.44. The word they in the passage refers to ______

填空题. The Structure of the Human Eye Comprised of more than thirty, major parts, the human eye ranks among the body's most intricately designed and complex organs. However, for simplicity's sake, this complicated body part can be reduced to its major components—the pupil, iris, lens, cornea, retina, and optic nerve—and their main functions. Each part plays a vital role in granting sight to a person. The most familiar parts of the eye are the pupil and the iris because they are easily visible when looking at a person's eyes. The pupil is the central hole that allows light to enter the eye. It typically changes size to permit entry to more or less light by contracting in bright light and expanding in dim light. The iris is the colored area of the eye surrounding the pupil and is the part which controls the contracting and expanding of the pupil thanks to muscles connected to it that enable the iris to open and close. The cornea and lens let the eye focus light in particular ways after it enters the eye. The cornea is located in front of the pupil and iris while the lens lies behind them. The cornea is a curved, transparent structure that bends light toward the pupil. On account of this function, the cornea has no blood vessels that could potentially cloud it, so it receives nutrients from the watery tears that cover the eye whenever a person blinks. As for the lens, it takes the light entering the pupil and focuses it toward the back of the eye in the direction of the retina. The lens has the ability to change shapes to focus on objects at various distances. The retina is formed by sensitive photoreceptor cells called rods and cones, which form the images that a person sees through the pupil. The rods handle black and white images and are used mostly in situations involving dim light while the cones are responsible for images requiring colored light. As images form on the retina, they are instantaneously sent along the optic nerve to the brain, where they are interpreted as what a person sees. *component: a piece or pad of something larger *cloud: to make blurry7. The author discusses the iris in paragraph 2 in order to ______

填空题2. The Expanding Universe Theory The Big Bang Theory, which posits that the universe began from a single point of incredibly dense matter, is the most widely accepted theory regarding the creation of the universe. According to it, roughly fourteen billion years ago, this matter exploded and expanded to form the present-day universe. This theory is based upon observations of the universe suggesting that it is not static but is instead continually expanding outward. For centuries, astronomers believed that the universe was fixed and that Earth was located at its center. By the early twentieth century, the notion that Earth was at the center of the universe had been dispelled, but the static universe theory was still the prevailing model. Even Albert Einstein was a great believer in it. Then, in 1917, he had a revelation. His general theory of relativity did not precisely agree with the static universe model, yet he could not reconcile his strong belief in a static universe with his theories, so he concluded that some unknown force was preventing the universe from expanding. Simultaneously, other astronomers were discovering that Earth and the sun belonged to a large collection of stars they called a galaxy. In 1925, American astronomer Edwin Hubble proved other galaxies existed in addition to Earth's galaxy, which had been dubbed the Milky Way. Hubble made further observations that had a profound effect on the static universe theory. In 1929, he realized that the light coming from the galaxies he was observing had a distinctive red shift on the light spectrum. This was due to the Doppler Effect, which makes an object moving away from an observer appear red in color. This meant that the galaxies were moving away from one another and that the universe was expanding outward. There was resistance to Hubble's theory, but Einstein accepted it, and others soon agreed with the expanding universe theory as well. From it, astronomers concluded that if the universe was expanding, then it must have been much smaller at some point. That led to the Big Bang Theory becoming the accepted model for the creation of the universe. *static: stationary; unmoving *Doppler Effect: a shift in the frequency of the radiation emitted by a source that is moving relative to an observer An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas of the passage. Some sentences do not belong because they express ideas that are not presented in the passage or are minor ideas in the passage. Thanks to discoveries made by astronomers in the twentieth century, the expanding universe model replaced the static universe model as accepted science, ANSWER CHOICES ①Edwin Hubble made a discovery that showed that the galaxies in the universe were spreading apart from one another. ②The theory of relativity showed Albert Einstein that his notion that the universe was static was incorrect. ③Most people throughout history have believed that the universe is static and that Earth can be found at its center. ④The belief in the expanding universe model indicated to astronomers that the universe was probably started due to the Big Bang. ⑤Albert Einstein and Edwin Hubble worked together to come up with the expanding universe model. ⑥The Doppler Effect is what makes an object appear red when it is moving away from another object.

填空题.The First Talkies Motion pictures were invented late in the nineteenth century, yet it was not until the 1920s that they featured sound. Prior to then, movies were silent but were usually accompanied by printed words or subtitles on the screen to serve as dialogue or descriptions. Many theaters additionally employed a piano player or music record player to provide live music during the showing of a film. Silent film actors were famed for their ability to show expressive emotions rather than to recite dialogue, such as what was done during staged dramatic performances. When the first sound motion pictures—talkies—came out, however, the landscape of the motion picture industry changed forever. Since motion pictures were invented, people desired to include sound along with the moving images. Some early devices utilized sound discs, which were similar to record albums, to produce sounds for short films; however, the difficulty was getting the sounds and images to synchronize. This was a problematic task because both had to be started at precisely the same moment for the sounds and images to match. Due to this problem, the motion picture industry searched for a way to put sounds and images onto a single medium. By 1920, several European inventors had experienced minor success in putting sound waves on celluloid film strips, but the technology was deemed inadequate for large-scale motion pictures. Meanwhile, in the United States, inventor Lee de Forrest strived to perfect recording sound on celluloid, and, by the mid-1920s, he had solved the problem. He started producing short sound films for public exhibition. At the same time, other inventors successfully worked on sound on disc technology, which synchronized sounds on a record disc with the images in a film. The first major motion picture to take advantage of this system was Don Juan, which premiered in August 1926. It used recorded music and sound effects, yet it had no recorded dialogue, so it is usually not considered the first talkie. That honor went to The Jazz Singer, which was released in October 1927. It was the first major motion picture with prerecorded music, effects, and, in some scenes, singing and dialogue. The Jazz Singer used sound on disc technology, but the standard soon became sound on celluloid, or film, due to the better synchronization between sounds and images that it provided. At first, the big Hollywood studios resisted changing from silent movies to talkies. A major issue was that theaters, which were owned by many of the major studios then, were unequipped to project talkies, so converting them would be expensive. There were also difficulties on movie sets as directors and actors struggled with the new sound recording technology. Nevertheless the success of The Jazz Singer and other talkies changed their minds. In July 1928, Lights of New York, the first film with all its dialogue recorded and played for the audience, became a smash hit. Audiences were amazed by the new technology and clamored for more as they wanted to see their favorite stars singing and talking on the silver screen. For the next few years, studios continued to produce both silent movies and talkies. However, by the mid-1930s, most studios were only producing talkies as silent movies practically disappeared. *subtitle: words in a film that are printed at the bottom of a screen *synchronize: to match; to coordinate *smash hit: a huge success; a bestseller36. Vocabulary ______=to repeat something from memory

填空题. Pacific Island Plant and Animal Migration The Pacific Ocean is covered by a vast archipelago of islands that are spread out in long chains covering thousands of kilometers with some close to large landmasses and others much farther away. When European explorers chanced upon these islands, almost all of them were inhabited, and most had significant amounts of vegetation as well as large populations of various species of animals. Because nearly all of these islands were created by volcanic activity, such life—both plant and animal—would have been absent from them when they rose above the ocean's surface. The plants and animals living on them migrated from elsewhere by both air and sea. In many cases, they accomplished this on their own, but some of them got helping hands from humans. Plant life on the desolate volcanic Pacific islands most likely initially arrived due to the wind. Small seeds such as thistle seeds and the spores of ferns are lightweight enough to have been carried aloft great distances whereas heavy seeds would have had more difficulty being transported that way, especially to remote, isolated islands such as Easter Island and the Galapagos Islands. The latter group has many lichens, ferns, and mosses, which all grow from light spores, yet it has few vascular plants, which have heavier seeds. As for vascular plant life, it could have arrived on other islands through two ways: by water or birds. The coconut tree is widespread throughout the Pacific islands in spite of its enormous seeds being too heavy to be carried by the wind, yet it is light enough to float, so it has moved all across the ocean in that way. Birds may have also consumed various heavy seeds, flown to islands, and then defecated the seeds onto these new lands, whereupon they then began to grow. There may not have been suitable soil for seeds to grow in on these volcanic islands at first, but, over time, as new plant life arrived, the soil was sufficiently broken up and filled with nutrients, thereby allowing many plant species to take root. Similarly, animals arrived by air and sea. The birds that first arrived on the Pacific islands indisputably flew from nearby larger landmasses. Over many generations, they could have island-hopped from one place to another. Small insects—and possibly tiny invertebrates—may have been light enough to be windblown to various islands. Certainly, sea creatures such as turtles and penguins arrived on the islands by swimming to them. Small mammals and reptiles may have arrived on them by water, most likely after floating on rafts of dense vegetation that were blown out to sea during strong storms. Some species of mice have been known to do this, and lizards have also been found on rafts far from their native homelands. Today, many Pacific islands are home to a wide variety of plants and animals that reside throughout the rest of the world. The reason is that they were brought to the islands as a result of human migration. Over thousands of years, people spread from mainland Asia into the Pacific islands as they reached as far south as New Zealand, as far east as Easter Island, and as far north as Hawaii. During these great migrations, people took their plants and animals with them. One example is the chicken, which is found virtually everywhere in the Pacific today because it was transported in large canoes from island to island. The pig was also widespread throughout the Pacific and became an important source of protein for Pacific islanders. Some animals, such as mice, were most likely stowaways on islanders' canoes. Furthermore, people took their staple plants, such as taro and yams, which they planted on the islands as they slowly made their way across the Pacific Ocean. The Pacific natives were not the only ones who contributed to animal and plant migration as Europeans also played a role of their own. Unfortunately, European explorers brought many animals that caused disruptions on the islands. ❶Dogs, rats, snakes, and cats, for instance, hunted many species of small mammals and birds to extinction. ❷Plant eaters such as goats and sheep had negative effects on small islands' vegetation as well. ❸Nevertheless, these new animals provided some benefits. ❹Goats and sheep, for instance, became important to the settlements of Europeans on New Zealand.28. in paragraph 1, the author implies that many of the Pacific islands ______

填空题. Woodrow Wilson's Economic Policies Woodrow Wilson served as the president of the United States from 1913 to 1921. While he is mostly remembered for leading the country into World War Ⅰ and for his peace efforts following the war, he was also heavily involved in domestic affairs, particularly those regarding the American economy. During his presidency, the Federal Reserve banking system was established, antitrust laws were strengthened, tariff reforms were instituted, and the first broad income tax became law. Qn top of those measures, the eight-hour workday was established, and financial assistance was provided to farmers during Wilson's two terms in office. One of Wilson's first moves toward economic reform was the Revenue Act of 1913, which had two objectives: the lowering of tariffs and the implementing of a broad income tax on all sources of income. The income tax was intended to maintain government revenues that would be lost through the lowering of tariffs. The income tax had become law once the Sixteenth Amendment was ratified in February 1913, one month prior to Wilson taking office; however, the details of the new law had not been worked out yet. Wilson's government proposed a one-percent tax on all annual incomes exceeding $4,000 for couples and $3,000 for singles. ❶The new law also allowed higher taxes to be levied on those earning greater incomes. ❷And it lowered tariffs on foreign goods, which was done in the hope of increasing international trade. ❸The immediate effectiveness of this act on the American economy is difficult to calculate though because the outbreak of World War Ⅰ in 1914 tremendously upset global trade.❹ Wilson additionally set his sights on reforming the American banking system. Most American banks were private enterprises, and numerous banks had failed, leaving their depositors impoverished when all their savings were lost. Wilson was determined to create a federal banking system which would have a wide range of responsibilities, among them protecting people's savings and serving as the government's bank. This new bank would additionally be the only legal authority permitted to issue American money. After considerable debate, the Federal Reserve Act was passed in December 1913. Antitrust reform and consumer protection were Wilson's next targets. During his time, many of the largest American companies dominated certain aspects of the economy, including oil, steel, and shopping. Antitrust laws were designed to halt these practices, which they accomplished with the breakup of Standard Oil into several small companies in 1911. The court system handled antitrust cases, but Wilson believed they should be the responsibility of a regulatory body that would oversee all such business practices. Therefore, the Federal Trade Commission was established in 1914 to regulate competition between companies and to protect consumers from unfair business practices. Wilson continued to focus on reforming the American economy when he tackled two more major issues, agriculture and labor laws. Farming was the livelihood of a great majority of Americans in the 1910s, but farms were notoriously susceptible to instability, suffering both good and bad years. Most farmers were cash poor and unable to improve their farms or equipment. Banks frequently refused to lend money to farmers, or, if they did, the loans were short term and had interest rates that were ruinous in nature. The Federal Farm Loan Act of 1916 was passed to enable farmers to borrow money by using their land as collateral. Under this act, farmers could borrow up to $10,000 at low interest rates and had up to forty years to repay the funds. The main results were the revitalization of the small American farmer and the protection of these farmers from absorption by big agricultural companies. Labor reform during Wilson's administration came about due to a threatened major railway strike in 1916 that was averted only when workers were promised an eight-hour workday, which would reduce the work they did on a daily basis. This established a precedent that later led to most workers getting eight-hour workdays. Wilson attempted to reform child labor laws through the Keating-Owen Labor Act of 1916, but the Supreme Court ruled it was unconstitutional and struck it down in 1918. Despite this setback, Wilson's economic reforms as a whole had a significant and long-lasting impact on the American economy.44. In paragraph 1, the author's description of Woodrow Wilson mentions all of the following EXCEPT: ______

填空题.Attila the Hun Attila the Hun was the leader of a tribe of Eurasian nomads that invaded the Roman Empire in the mid-fifth century. Around 370 A.D., the Huns appeared from east of the Volga River and settled in the land that is Hungary today. They warred against Rome and other tribes, and they overran parts of the Eastern Roman Empire before invading the Western Roman Empire while under Attila's command. They employed mounted archers to engage in mobile warfare, and they developed reputations for being fierce warriors from whom others fled in terror. Eventually, the Romans themselves branded Attila with the moniker "The Scourge of God." Attila's birthdate is uncertain, but some historians place it around 406. Two of Attila's uncles ruled together as they followed a common practice of the Huns involving joint-rule by brothers. During that period, the Huns had a cordial relationship with the Eastern Romans, who employed the Huns as mercenaries for their wars with the barbaric tribes pushing against the empire's northern borders. In 434, both of Attila's uncles died, so Attila and his older brother Bleda became the co-rulers of the Huns. After the initiation of some troubles with the Eastern Roman empire, the brothers negotiated a peace that brought the Huns a great amount of wealth in the form of tribute and the ransoming of Roman prisoners. But this peace only lasted until 440, when the Huns and the Eastern Roman Empire began battling each other again. ❶By 443, the Hun army had marched to the walls of Constantinople, the capital of the Eastern Roman Empire, but the soldiers could not get past the prominent defenses; however, they had defeated Roman field armies, so, once again, the Romans negotiated a peace requiring them to pay a much larger tribute of gold and higher ransoms for prisoners. ❷Satisfied, the Huns returned to their homelands. ❸Then, in 445, Bleda died, leaving Attila as the sole ruler.❹ Attila then set out on his greatest campaign: the invasion of the Western Roman Empire. The impetus for the invasion was a marriage. In 450, Honoria, the sister of Valentinian, the emperor of the Western Roman Empire, had written to Attila and requested his assistance because she wished to avoid an arranged marriage to a Roman senator. Attila interpreted her plea as a marriage proposal, claimed Honoria as his bride and half her brother's empire as her dowry, and invaded the west. The Huns marched through the Germanic lands and invaded Gaul while allying with other tribes along the way. Attila's vast host met the Romans and their Visigoth allies at the Battle of Chalons in 451. The battle ended in a stalemate but effectively terminated the Huns' invasion of Gaul. A year later, a problem with supplies resulted in a failed invasion of northern Italy, which led to a decline in the Huns' fortunes. Thwarted in his attempt to marry Honoria, Attila took a new bride from a Germanic tribe in 453. However, during his wedding night feast, Attila suffered a seizure and died. Some historians speculate that poison was the cause while others attribute his death to heavy drinking. Whatever the case, Attila's heirs fought over who would rule the Huns, which divided them and resulted in the ultimate defeat of the Huns at the hands of a confederation of Germanic tribes. *cordial: friendly *dowry: money or other items of value a bride gives to her husband when they are married28. Vocabulary ______=to name

填空题2. Carnivorous Plant Traps Most plants obtain nourishment through photosynthesis, but some species actually consume other living things for sustenance. The majority of these plants grow in regions with rocky terrain or bogs, where the soil lacks nutrients, so they utilize a couple of methods to catch their prey, which are primarily insects and small vertebrates. The two hunting methods these carnivorous plants use are active traps and passive traps. An active carnivorous plant trap involves some type of movement by the plant when capturing prey. The best-known plant with this kind of trap is the Venus flytrap, which has clamshell-like leaves that snap closed on animals landing on them. The plant has tiny glands that produce nectar on the open faces of its leaves and therefore attract animals. The leaves have small surface hairs that act as trigger mechanisms, so when an animal sucking the nectar touches them more than once in a short period of time, the trap swiftly shuts, capturing the animal. The leaf next releases enzymes that slowly digest the creature over a period of three to five days. The waterwheel plant is another carnivorous plant that catches animals in a similar manner. Its trap, however, is smaller than that of the Venus flytrap and exclusively captures underwater invertebrates. Most carnivorous plants use passive traps, so no movement is required to capture their prey. The flypaper trap, utilized by sundews and butterworts, is one such passive trap. A leaf or tentacle-like protrusion has a sticky substance—called mucilage—on it, and it acts like sweet nectar to attract prey that subsequently gets stuck in the mucilage of the flypaper trap. Other passive carnivorous plants include the various species of pitcher plants, each of which has a deep hollow resembling a water pitcher. Toxic nectar attracts prey to the plant's rim, where the creatures, after consuming the nectar, become disoriented and fall into the hollow of the plant. Downward-pointing, stiff bristle-like hairs prevent them from crawling back up, and they are consequently slowly digested inside the plant. *vertebrate: an animal that has a backbone *mucilage: a liquid gummy secretion of a plant Select the appropriate statements from the answer choices and match them to the carnivorous plant trap to which they relate. TWO of the answer choices will NOT be used. STATEMENTS ①Requires part of the trap to move to capture its prey ②Includes the traps used by the butterwort and pitcher plant ③May require a long period of time to catch its prey ④Is the type of trap that is used by the waterwheel plant ⑤Can involve the use of tiny hairs that trigger a trap when they move ⑥Is used by the sundew and the cobra plant to catch animals ⑦May involve the utilization of nectar that is poisonous to prey

填空题John B

填空题.How Animals Regulate Their Body Temperatures Both land and water animals possess a variety of ways to regulate their body temperatures to avoid overheating or freezing. Nearly all mammals and birds are endotherms that can control their internal body temperatures without external means. In contrast, most reptiles, amphibians, and fish are ectotherms that require external sources to adjust their body temperatures. Mammals and birds maintain their body temperatures mainly through the metabolizing of food, which generates internal heat. In extreme environments, however, they rely on other methods. The fur of most mammals acts like a warm coat, and mammals living in polar climates, such as polar bears, walruses, and seals, additionally have thick layers of blubber providing them with extra protection. Birds' feathers act in a similar manner and also keep water away from their skin, thereby preventing them from getting too cold. Numerous mammals and birds build lairs or nests that can keep them warm in frigid conditions, too. In tropical zones, many endotherms sweat to make their skin cooler and to draw heat from their bodies. Most fur-bearing mammals cannot sweat well and therefore pant through the mouth, which increases the evaporation that removes heat and cools their bodies. As for birds, they may flap their wings close to their throats to cool down.

填空题.The Western and Eastern Roman Empires At the height of its power, the Roman Empire was so immense that Emperor Diocletian divided the empire into western and eastern halves in 285. The Western Roman Empire was based in Rome while the Eastern Roman Empire later had its capital in Constantinople. Over time, the two empires exhibited distinct methods of rule reflecting their regions. Eventually, the Western Roman Empire fell to barbarian invaders in the late fifth century whereas the Eastern Roman Empire evolved into the Byzantine Empire, which survived for more than 1,000 years before being conquered by the Ottoman Turks in 1453. Diocletian opted to divide the empire primarily due to the unwieldiness of ruling a huge amount of territory. By 285, the Roman Empire covered all of Southern Europe and parts of Western Europe, Northern Africa, and the Middle East. Despite having an extensive network of roads and secure shipping lanes, communications were terribly slow. Messages from Rome could take weeks to reach their destinations. Thus provincial governors had a level of autonomy that practically made them minor emperors. A series of conflicts in the decades prior to the split also showed the weakness of far-flung military commands as invasions by border people in the east and west were barely beaten back. In such conditions, local military commanders had to wield absolute power to respond promptly to threats. Such power went to the heads of some of them to the point that generals contemplating usurping the throne were constant threats to the imperial throne. The forming of two empires, each led by a different ruler, was meant to end these problems and to bring stability by giving each emperor more control than a single ruler could wield. The reforms accomplished Diocletian's objectives to some degree, but the split also led to great differences between the two halves of the once-united empire. Diocletian had intended for the Eastern ruler to be subordinate to the Western one, but, over time, every emperor ruled as if his empire were separate. This was exacerbated by the differences between the two lands. For instance, despite being a part of the Roman Empire, Greece had dominated the eastern Mediterranean world for centuries. Hence it was natural that the Greek language and Greek customs replaced the Latin language and Roman customs in the Eastern Roman Empire. Further problems centered on economic differences between the two halves. The eastern empire was urban based and derived its wealth from trade and work done by artisans. The western empire was more rural and agricultural, and its wealth depended on large populations of people working the land. In time, this weakness led to the decline of the western empire as waves of barbarian invaders devastated the population and land. Diocletian also initiated economic reforms by raising taxes to fund the defense of the empire. In the west, tax collectors had problems getting money from the rural populace, who were spread out, had little currency, and preferred paying taxes in farm produce. In the east, most people lived in cities and had hard currency, so tax collectors had an easier time, making money pour into Constantinople. The end result was a rich, stable Eastern Roman Empire that withstood multiple invasions for a millennium and a poor, unstable Western Roman Empire that succumbed to invasion fewer than two centuries after the split. *shipphing lane: a region of water, especially in an ocean or sea, in which numerous ships sail *exacerbate: to make worse13. Vocabulary ______=awkwardness

填空题.The Roman Conquest of Italy The Roman Empire had its origins in a small village alongside the Tiber River. Over time, the village increased in size to become a town and, later, a city, whereupon it was ruled by a series of kings—seven according to tradition—for more than two centuries. In 509 B.C., however, the people of Rome deposed the last king and established a republican system of government. During the next 250 years, the Romans proceeded to dominate Latium, the land around their city, and then conquered the entire Italian peninsula. In the early years after the foundation of the Roman Republic, the Romans were confined to a narrow strip of land around their city and the Tiber River. During the next couple of centuries, the city expanded slowly because of the numerous warlike tribes and city-states located nearby. Rome's primary enemy, which it ultimately conquered in 396 B.C., was the city-state of Veii; nevertheless, Rome's victory did not ensure peace because, in 390 B.C., the Gauls, another barbarian tribe, invaded Italy and conquered numerous city- states, including Rome, which they sacked. Fortunately for the Romans, the Gauls were concerned with looting rather than conquest, so they departed afterward. Sensing Rome's weakness following that defeat, a group of Latium city-states called the Latin League rose in rebellion, but the Romans crushed them. Next, Rome dealt with the Samnites, a tribe of warriors in southern Italy who threatened the city-state of Campania, which beseeched Rome for help. The Samnites heartily resisted Roman attacks, so the warfare between them and Rome lasted decades and required three long wars before the Romans emerged triumphant in 290 B.C. The Roman army attempted to employ the Greek phalanx as its tactical formation, yet it was ill-suited for fighting the Samnites in their hilly homeland. The Romans consequently adopted the looser Samnite formation of smaller tactical units equipped with javelins and short swords, which enabled them to defeat the Samnites, and then those weapons were used by the Roman legions for centuries. By that time, most of the Italian peninsula, except for the extreme southern part, where Greek city-states had established many colonies, was under Roman control. Fearing Rome, the city-states there banded together and, in 280 B.C., hired an army led by King Pyrrhus of Epirus. ❶Pyrrhus defeated the Romans several times, but his own armies suffered great losses as well. ❷In spite of these setbacks, Rome refused to surrender, and a Roman army finally defeated Pyrrhus's army in 272 B.C. ❸This was the last major enemy Rome faced in Italy, so almost the entire peninsula was possessed by Rome by 265 B.C.❹ After vanquishing their foes, the Romans needed to retain power over them, and they accomplished this by being benevolent masters rather than cruel conquerors. They gave most defeated people the opportunity to become Roman citizens, thereby entitling them to numerous benefits. Additionally, Roman soldiers were granted land in occupied regions, so they remained in those places as farmers. This policy had two advantages. First, the Romans served as a force of experienced soldiers who could swiftly form military units to quell any rebellions that started. It also infused the conquered people with individuals loyal to Rome who, over the course of time, married local women and had families that themselves became loyal to Rome. *sack: to pillage or loot after taking control of a place *phalanx: a group of heavily armed infantry that fight closely together while joining their shields28. Vocabulary ______=to control; to rule over