单选题Water From the beginning, water has furnished man with a source of food and a highway to travel upon. The first 16 arose where water was a dominant element in the environment, a challenge to man"s ingenuity. The Egyptians invented the 365-day calendar 17 the Nile"s annual flooding. The Babylonians, who were among the most famous law-makers in ancient times, invented laws 18 water usage. Water inspired the Chinese to build a 1,000- 19 canal, a complex system which, after nearly 2,500 years, remains still practically 20 and still commands the astonishment of engineer. But the 21 never found complete solutions to their water problems. The Yellow River is also known 22 "China"s Sorrow"; it is so unpredictable and dangerous 23 in a single flood it has caused a million 24 . Floods slowed the great civilization of the Indus River Valley, and inadequate drainage ruined 25 of its land. Today water dominates 26 as it always has done. Its presence continues to 27 the location of his homes and cities; its violent variability can 28 man of his herds or his crops; its routes links him 29 his fellows; its immense value may 30 to already dangerous political conflicts. There are many examples of this in our own time.

单选题It"s impolite to cut in when two person are holding a conversation.

单选题According to the passage, sea-water can be turned into fresh water by

单选题Scientists, who are now aware of how nautiluses regulate their buoyancy, have been able to dispel erroneous ideas about these creatures.

单选题The Exploding Lakes of Cameroon What comes to mind when you think of a lake? You probably imagine a pretty scene with blue water, birds, and fish. For the people in the northwestern Cameroon, however, the image is very different. For them, lakes may mean terrible disasters. In 1984, poisonous gases exploded out of Lake Monoun and came down into the nearby villages, killing thirty-seven people. Two years later, Lake Nyos erupted a cloud of gases rolled down the hills and into the valleys and killed 1,700 people. Lake Nyos and Lake Monoun are crater (火山口) lakes. They were formed when water collected in the craters of old volcanoes. The volcanoes under Lake Nyos and Lake Monoun are not active anymore. However, poisonous gases from the center of the earth continue to flow up through cracks in the bottom of the lake. This is normal in a crater lake. In most crater lakes, these gases are released often because the water "turns over" regularly. That is, the water from the bottom of the lake rises and mixes with the water at the top, allowing the gases to escape slowly. However, in Lakes Nyos and Monoun, there is no regular turning over. No one knows the reason for this fact, but as a result, these lakes have more gases tapped at the bottom than other crater lakes. In fact, scientists who have studied Lakes Nyos and Monoun have found 16,000 times more gases. When a strong wind, cool weather a storm, or a landslide causes the water to turn over suddenly, the gases escape in a violent explosion. In the past, no one knew when the gases might explode, so there was no way for the villagers to escape disaster. Now scientists from the United States, France, and Cameroon have found a way to reduce the gas pressure at the bottom of Lake Nyos. They stood a 672-foot plastic pipe in the middle of the lake, with one end of the pipe near the bottom and the other end in the air. Near the top of the pipe, the team put several holes that could be opened or closed by a computer. Now, when the gas pressure gets too high, the holes are opened and some of the gas-filled water shoots up through the pipe into the air like a fountain. With less pressure, a disastrous explosion is much less likely. However, the scientists are not sure that one pipe will be enough to prevent explosions. They hope to put in others soon and they plan to install a similar pipe and a computer system at Lake Monoun as well. To protect people nearby until all of the pipes are in place, the scientists have installed early warning systems at both lakes. If the gas pressure rises to a dangerous level, computers will set off loud sirens (警报) and bright lights to warn the people in the villages. That way, they will have time to escape from the dangerous gases.

单选题I could recognize the old car at a glance. A．square B．feature C．flame D．glimpse

单选题Pilots flying at the height of more than 2,100 meters saw a thick black column of ash and steam shooting up into the air from the crater.

单选题High wages and {{U}}restrictive{{/U}} work practices are said to have created new nonunion competition.

单选题Anderson left the table, {{U}}remarking{{/U}} that he had some work to do. A. doubting B. thinking C. saying D. knowing

单选题Mother Nature Shows Her Strength Tornadoes (龙卷风) and heavy thunderstorms moved across the Great Lakes and into Trumbull County on Saturday evening. The storms were dramatic and dangerous. George Snyder was driving the fire truck down Route 88 when he first noticed that a funnel (漏斗状的) cloud was behind him. "I stopped the truck and watched the funnel cloud. It was about 100 feet off the ground and I saw it go up and down for a while. It was moving toward Bradley Road and then suddenly it disappeared," Snyder said. Snyder only saw one of the funnel clouds that passed through northeastern Ohio on Saturday. In Trumbull County, a tornado turned trees onto their sides. Some trees fell onto houses and cars. Other trees fell into telephone and electrical wires as they went down. Amanda Symcheck was having a party when the storm began. "I knew something was wrong," she said. "I saw the sky go green and pink (粉红色). Then it sounded like a train rushing toward the house. I started crying and told everyone to go to the basement for protection." The tornado caused a lot of damage to cars and houses in the area. It will take a long time and much money to repair everything. There was also serious water damage from the thunderstorms. The heavy rains and high wind caused the power to go out in many homes. The storms caused serious flooding in areas near the river. More than four inches of rain fell in parts of Trumbull County. The river was so high that the water ran into streets and houses. Many streets had to be closed to cars and trucks because of the high water. This made it difficult for fire trucks, police cars, and other rescue vehicles to help people who were in trouble. Many people who live near the river had to leave their homes for their own safety. Some people reported five feet of water in their homes. Local and state officials opened emergency shelters for the people who were evacuated (撤走). The Red Cross served meals to them. "This was a really intense storm," said Snyder, "People were afraid. Mother Nature can be fierce. We were lucky this time. No one was killed."

单选题The last few weeks have been enjoyable.

单选题The Mona Lisa, ______ in Italy, is now in the Louvre, a museum in Pads.A. who paintedB. who was paintedC. which paintedD. which wag painted

单选题California Gives Green Light to Space Solar Power Energy beamed down from space is one step closer to reality, now that California has given the green light to an agreement that would see the Pacific Gas and Electric Company buy 200 megawatt (兆瓦) of power beamed down from solar-power satellites beginning in 2016. But some major challenges will have to be overcome if the technology is to be used widely. A start-up company called Solaren is designing the satellites, which it says will use radio waves to beam energy down to a receiving station on Earth. The attraction of collecting solar power in space is the almost uninterrupted sunshine available in eosynchronous (与地球同步的) orbit. Earth-based solar cells, by contrast, can only collect sunlight during daytime and when skies are clear. But space-based solar power must grapple (努力克服) with the high cost per kilogram of launching things into space, says Richard Schwartz of Purdue University in West Lafayette, Indiana, "If you're talking about it being economically viable or power of the Earth, it's a tough go." he says. Cal Boerman, Solaren's director of energy services, says the company designed its satellites with a view to keeping launch costs down. "We knew we had to come up with a different, revolutionary design," he says. A patent the company has won describes ways to reduce the system's weight, including using inflatable minors to focus sunlight on solar cells, so a smaller number can collect the same amount of energy. But using minors introduces other Henges, including keeping the solar cells from overheating, says Schwartz. "You have to take care of heat dissipation (散发) because you're now concentrating a lot of energy in one place," he says. According to the company's patent, Solaren's solar cells will be connected to radiators to help keep them cool. Though Boerman says the company believes it can make space-based solar power work, it is not expecting to crowd out other forms of renewable energy. Laws in California and other states require increasing use of renewable energy in coming years, he points out. "To meet those needs, we're going to need all types of renewable energy sources," he says.

单选题We should be {{U}}cautious{{/U}} in crossing a crowded street.

单选题阅读下面这篇短文，短文后列出了7个句子，请根据短文的内容对每个句子做出判断。 {{B}} Mother Nature Shows Her Strength{{/B}} Tornadoes (龙卷风) and heavy thunderstorms moved across the Great Lakes and into Trumbull County on Saturday evening. The storms were dramatic and dangerous. George Snyder was driving the fire truck down Route 88 when he first noticed that a funnel (漏斗状的) cloud was behind him. "I stopped the truck and watched the funnel cloud. It was about 100 feet off the ground and I saw it go up and down for a while. It was moving toward Bradley Road and then suddenly it disappeared," Snyder said. Snyder only saw one of the funnel clouds that passed through northeastern Ohio on Saturday. In Trumbull County, a tornado turned trees onto their sides. Some trees fell onto houses and cars. Other trees fell into telephone and electrical wires as they went down. Amanda Symcheck was having a party when the storm began. "I knew something was wrong," she said." I saw the sky go green and pink (粉红色). Then it sounded like a train rushing toward the house. I started crying and told everyone to go to the basement for protection." The tornado caused a lot of damage to cars and houses in the area. It will take a long time and much money to repair everything. There was also serious water damage from the thunderstorms. The heavy rains and high wind caused the power to go out in many homes. The storms caused serious flooding in areas near the river. More than four inches of rain fell in parts of Trumbull County. The river was. so high that the water ran into streets and houses. Many streets had to be closed to cars and trucks because of the high water. This made it difficult for fire trucks, police cars, and other rescue vehicles to help people who were in trouble. Many people who live near the river had to leave their homes for their own safety. Some people reported five feet of water in their homes. Local and state officials opened emergency shelters for the people who were evacuated (撤走). The Red Cross served meals to them. "This was a really intense storm," said Snyder. "People were afraid. Mother Nature can be fierce. We were lucky this time. No one was killed."

单选题 Change Poses Major Risks for Unprepared Cities A new examination of urban policies has been carried out recently by Patricia Romero Lankao. She is a sociologist specializing in climate change and {{U}} {{U}} 1 {{/U}} {{/U}}development. She warns that many of the world's fast- growing urban areas, especially in developing countries, will likely suffer from the {{U}} {{U}} 2 {{/U}} {{/U}}of changing climate. Her work also concludes that most cities are failing to {{U}} {{U}} 3 {{/U}} {{/U}}emissions of carbon dioxide and other greenhouse gases. These gases are known to affect the atmosphere. "Climate change is a deeply local issue and poses profound {{U}} {{U}} 4 {{/U}} {{/U}}to the growing cities of the world," says Romero Lankao. "But too few cities are developing effective strategies to protect their residents." Cities are {{U}} {{U}} 5 {{/U}} {{/U}}sources of greenhouse gases. And urban populations are likely to be among those most severely affected by future climate change. Lankao's findings highlight ways in which city-residents are particularly vulnerable, and suggest policy interventions that could offer immediate and longer-term {{U}} {{U}} 6 {{/U}} {{/U}} The locations and dense construction patterns of cities often place their populations at greater {{U}} {{U}} 7 {{/U}} {{/U}}for natural disasters. Potential threats associated with climate include storm surges and prolonged hot weather. Storm surges can flood coastal areas and prolonged hot weather can heat {{U}} {{U}} 8 {{/U}} {{/U}}paved cities more than surrounding areas. The impacts of such natural events can be more {{U}} {{U}} 9 {{/U}} {{/U}}in an urban environment. For example, a prolonged heat wave can increase existing levels of air pollution, causing widespread health problems. Poorer neighborhoods that may {{U}} {{U}} 10 {{/U}} {{/U}}basic facilities such as drinking water or a dependable network of roads, are especially vulnerable to natural disasters. Many residents in poorer countries live in substandard housing. {{U}} {{U}} 11 {{/U}} {{/U}}access to reliable drinking water, roads and basic services. "Local governments, therefore, should take measures to {{U}} {{U}} 12 {{/U}} {{/U}}their residents." Unfortunately, they tend to move towards rhetoric {{U}} {{U}} 13 {{/U}} {{/U}}meaningful responses, Romero Lankao writes. They don't impose construction standards that could reduce heating and air conditioning {{U}} {{U}} 14 {{/U}} {{/U}}. They don't emphasize mass transit and reduce automobile use. In fact, many local governments are taking a hands—off approach. {{U}} {{U}} 15 {{/U}} {{/U}}, she urges them to change their idle policies and to take strong steps to prevent the harmful effects of climate change on cities.

单选题Which of the following statements about Eta Carinae is NOT true?

单选题She seemed to have detected some anger in his voice.A. noticedB. heardC. realizedD. got

单选题 下面的短文后列出了7个句子，请根据短文的内容对每个句子做出判断：如果该句提供的是正确信息，请选择A；如果该句提供的是错误信息，请选择B；如果该句的信息文中没有提及，请选择C。 A Great Quake Coming? Everyone who lives in San Francisco knows that earthquakes are common in the Bay Area--and they can be devastating．In 1906，for example，a major quake destroyed about 28,000 buildings and killed hundreds，perhaps thousands of people．Residents now wonder when the next“Big One”will strike．It's bound to happen someday．At least seven active fault(断层)lines run through the San Francisco area． Faults are places where pieces of Earth's crust(地壳)slide past each other．When these pieces slip，the ground shakes． To prepare for that day，scientists are using new techniques to reanalyze the 1906 earthquake and predict how bad the damage might be when the next one happens． One new finding about the 1906 quake is that the San Andreas fault split apart faster than scientists had assumed at the time．During small earthquakes，faults rupture(断裂)at about 2.7 kilometers per second．During bigger quakes，however．ruptures can happen at rates faster than 3.5 kilometers per second． At such high speeds，massive amounts of pressure build up，generating underground waves that can cause more damage than the quake itself．Lucky for San Francisco，these pressure pulses(脉冲)traveled away from the city during the 1906 event．As bad as the damage was，it could have been far worse． Looking ahead．scientists are trying to predict when the next major quake will occur．Records show that earthquakes were common before 1906．Since then，the area has been relatively quiet．Patterns in the data，however，suggest that the probability of a major earthquake striking the Bay Area before 2032 is at least 62 percent． New buildings in San Francisco are quite safe in case of future quakes．Still，more than 84 percent of the city's buildings are old and weak．Analyses suggest that another massive earthquake would cause extensive damage． People who live there today tend to feel safe because San Francisco has remained pretty quiet for a while．According to the new research，however．it's not a matter of“if”the Big One will hit．It's just a matter of when．

单选题Sharks Perform a Service for Earth"s Waters It is hard to get people to think of sharks as anything but a deadly enemy. They are thought to 1 people frequently. But these fish perform a 2 service for earth"s waters and for human beings. Yet business and sport fishing are threatening their 3 . Some sharks are at 4 of disappearing from earth. Warm weather may influence both fish and shark activity. Many fish swim near coastal areas 5 their warm waters. Experts say sharks may follow the fish into the same areas, 6 people also swim. In fact, most sharks do not purposely charge at or bite humans. They are thought to mistake a person 7 a sea animal, such as a seal or sea lion. That is why people should not swim in the ocean when the sun goes down or comes up. Those are the 8 when sharks are looking for food. Experts also say that bright colors and shiny jewelry may cause sharks to attack. A shark has an extremely good sense of smell. It can find small amounts of substances in water, such as blood, body liquids and 9 produced by animals. These powerful 10 help sharks find their food. Sharks eat fish, any 11 sharks, and plants that live in the ocean. Medical researchers want to learn more about the shark"s body defense and immune systems 12 disease. Researchers know that sharks 13 quickly from injuries. They study the shark in hopes of finding a way to fight human disease. Sharks are important for the world"s 14 . They eat injured and diseased fish. Their hunting activities mean that the numbers of other fish in ocean waters do not become too 15 . This protects the plants and other forms of life that exist in the oceans.