单选题Where Have All the Frogs Gone? In the 1980s, scientists around the world began to notice something strange: Frogs were disappearing. More recent research has shown that many kinds of amphibians (两栖动物) are declining or have become extinct. They have been around for a long time—over 350 million years. Why are they dying out now? Scientists are seriously concerned about this question. First of all, amphibians are an important source of scientific and medical knowledge. By studying amphibians, scientists have learned about new substances that could be very useful for treating human diseases. Further research could lead to many more discoveries, but that will be impossible if the amphibians disappear. The most serious aspect of amphibian loss, however, goes beyond the amphibians themselves. Scientists are beginning to think about what amphibian decline means for the planet as a whole. If the earth is becoming unlivable for amphibians, is it also becoming unlivable for other kinds of animals and human beings as we? Scientists now believe that amphibian decline is due to several environmental factors. One of these factors is the destruction of habitat, the natural area where an animal lives. Amphibians are very sensitive to changes in their habitat. If they cannot find the right conditions, they will not lay their eggs. These days, as wild areas are covered with houses, roads, farms, or factories, many kinds of amphibians are no longer laying eggs. For example, the arroyo toad (蟾蜍) of southern California will only lay its eggs on the sandy bottom of a slow-moving stream. There are very few streams left in southern California, and those streams are often muddy because of building projects. Not surprisingly, the arroyo toad is now in danger of extinction. There are a number of other factors in amphibian decline. Pollution is one of them. In many industrial areas, air pollution has poisoned the rain, which then falls on ponds and kills the frogs and toads that live there. In farming areas, the heavy use of chemicals on crops has also killed off amphibians. Another factor is that air pollution has led to increased levels of ultraviolet (UV) light. This endangers amphibians, which seem to be especially sensitive to UV light. And finally, scientists have discovered a new disease that seems to be killing many species of amphibians in different parts of the world. All these reasons for the disappearance of amphibians are also good reasons for more general concern. The destruction of land, the pollution of the air and the water, the changes in our atmosphere, the spread of diseases—these factors affect human beings, too. Amphibians are especially sensitive to environmental change. Perhaps they are like the canary (金丝雀) bird that coal miners once used to take down into the mines to detect poisonous gases. When the canary became ill or died, the miners knew that dangerous gases were near and their own lives were in danger.

单选题The way she looked after her young sister was really touching .

单选题Their style of playing football is utterly different.

单选题People in the little town lived a life of ease .

单选题{{B}}第三篇{{/B}} It is often claimed that nuclear energy is something we cannot do without. We live in a consumer society where there is an enormous demand for commercial products of all kinds. Moreover, an increase in industrial production is considered to be one solution to the problem of mass unemployment. Such an increase presumes an abundant and cheap energy supply. Many people believe that nuclear energy provides an inexhaustible and economical source of power and that it is therefore essential for an industrially developing society. There are a number of other advantages in the use of nuclear energy. Firstly, nuclear power, except for accidents, is clean. A further advantage is that a nuclear power station can be run and maintained by relatively few technical and administrative staff. The nuclear reactor represents an enormous step in our scientific evolution and, whatever the anti-nuclear group says, it is wrong to expect a return to more primitive sources of fuel. However, opponents of nuclear energy point out that nuclear power stations bring a direct threat not only to the environment but also to civil liberties. Furthermore, it is questionable whether ultimately nuclear power is a cheap source of energy. There have, for example, been very costly accidents in America, in Britain and, of course, in Russia. The possibility of increases in the cost of uranium (铀) in addition to the cost of greater safety provisions could price nuclear power out of the market. In the long run, environmentalists argue, nuclear energy wastes valuable resources and disturbs the ecology to an extent which could bring about the destruction of the human race. Thus, if we wish to .survive, we cannot afford nuclear energy. In spite of the case against nuclear energy outlined above, nuclear energy programmes are expanding. Such an expansion assumes a continual growth in industrial production and consumer demands. However, it is doubtful whether this growth, will or can continue. Having weighed up the arguments on both sides, it seems there are good economic and ecological reasons for sources of energy other than nuclear power.

单选题She gave up her job and started writing poetry.

单选题 Gross National Happiness In the last century, new technology improved the lives of many people in many countries. However, one country resisted these changes. High in the Himalayan mountains of Asia, the kingdom of Bhutan remained separate. Its people and Buddhist (佛教) culture had not been affected for almost a thousand years. Bhutan, however, was a poor country. People died at a young age. Most of its people could not read, and they did not know much about the outside world. Then, in 1972, a new ruler named King Jigme Singye Wangchuck decided to help Bhutan to become modem, but without losing its traditions. King Wangchuck looked at other countries for ideas. He saw that most countries measured their progress by their Gross National Product (GNP). The GNP measures products and money. When the number of products sold increases, people say the country is making progress. King Wangchuck had a different idea for Bhutan. He wanted to measure his country's progress by people's happiness. If the people's happiness increased, the king could say that Bhutan was making progress. To decide if people were happier, he created a measure called Gross National Happiness(GNH). GNH is based on certain principles that create happiness. People are happier if they have health care, education, and jobs. They are happier when they live in a healthy, protected environment. They are happier when they can keep their traditional culture and customs. Finally, people are happier when they have a good, stable government. Now these is some evidence of increased GNH in Bhutan. People are healthier and are living longer. More people are educated and employed. Tweenty-five percent of the land has become national parks, and the country has almost no pollution. The Bhutanese continue to wear their traditional clothing and follow their ancient Buddhist customs. Bhutan has also become a democracy. In 2008, King Wangchuck gave his power to his son. Although the country still had a king, it held its first democratic elections that year. Bhutan had political parties and political candidates for the first time. Finally, Bhutan has connected to the rest of the world through television and internet. Bhutan is a symbol for social progress. Many countries are now interested in Bhutan's GNH. These countries are investigating their own ways to measure happiness. They want to create new policies that take care of their people, cultures, and land. Brazil may be the next country to use the principles of GNH. Brazilian leaders see the principles of GNH as a source of inspiration. Brazil is a large country with a diverse population. If happiness works as a measure of progress in Brazil, perhaps the rest of the world will follow.

单选题We {{U}}derive{{/U}} information mainly from the Internet. A.deprive B.obtain C.descend D.trace

单选题When the tree falls, the monkeys scatter .

单选题As an assistant in a shop, she tries to be courteous at all times, even when she is very tired. A. straightforward B. polite C. flexible D. neat

单选题A local hypnotist (催眠师) offered his services, and Edgar readily accepted.

单选题He is considered to be the most Udiligent/U student in class.

单选题Choreographer Twyla Tharp uses familiar dance movements in original ways to create works filled with clever gestures and abrupt changes in motion and mood.

单选题Jean has determined notto attend the partyA. triedB. promisedC. decidedD. attempted

单选题During his lifetime he was able to {{U}}accumulate{{/U}} quite a fortune,

单选题The use of the chemical may present a certain hazard to the laboratory workers.

单选题The study also notes a steady decline in the number of college students taking science courses.

单选题{{B}}第二篇{{/B}} "Hidden" Species May Be Surprisingly Common Cryptic species animals that appear identical but are genetically quite distant—may be much more widespread than previously thought. The findings could have major implications in areas ranging from biodiversity estimates and wildlife management, to our understanding of infectious diseases and evolution. Reports of cryptic species have increased dramatically over the past two decades with the advent of relatively inexpensive DNA sequencing technology. Markus Pfenninger and Klaus Schwenk, of the Goethe-Universitat, in Frankfurt, Germany, analyzed all known data on cryptic animal species and discovered that they are found in equal proportions throughout all major branches of the animal kingdom and occur in equal numbers in all biogeographieal regions. Scientists had previously speculated that cryptic species were predominantly found in insects and reptiles, and were more likely to occur in tropical rather than temperate regions. "Species that are seemingly widespread and abundant could in reality be many different cryptic species that have low populations and are highly endangered. " Says Pfenninger. Until the genetic information of all species in at least one taxon is thoroughly studied, no one will know just how many cryptic species exist. "It could be as high as 30%. " Pfenninger says. "I'm extremely surprised by their results. " Says Alex Smith of the University of Guelph in Ontario, Canada. "It's a call to arms to keep doing the broad kind of genetic studies that we are doing. " Sampling as many individuals as possible, scientists hope to complete work on all fish and birds in another 5 to 10 years. Once either of these taxonomic groups is completed, Pfenninger says researchers will be able to decide how many cryptic species exist throughout the animal kingdom. Examples of cryptic species include the African elephant. A 2001 study found the elephants were actually two genetically distinct, non-interbreeding species, the African bush elephant and the African elephant. The species are currently listed as vulnerable and threatened, respectively, by the World Conservation Union (WCU). The reclassifications are more than an academic exercise. They define populations that have evolved independently of each other and whose genetic differences can have significant consequences. In the early 1900s misidentification of mosquito species based on morphology confused attempts to control malaria in Europe. Ultimately, what was thought to be a single species was actually made up of six sibling species, only three of which transmitted the disease. "The basic unit in biology is always the species, and you have to know what you are dealing with. " Pfenninger says. Much previous research is now no longer used, he says, because it is not clear what species was being studied.

单选题"They" in the second line of the last paragraph refers to

单选题Did you do that to irritate her?