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下列短文中有十个空白，每个空白有四个选项。根据上下文要求选出最佳答案。 The basic principle of radar is illustrated by what happens when one shouts in a cave. The echo of the shouting (11) the walls helps a person determine the size of the cave. With radar，however，the waves are radio waves instead of (12) waves. Radio waves travel (13) the speed of light，about300,000 kilometers in a second. A radar set (14) a short burst of radio waves. Then it receives the echoes (15) when the waves bounce(反射)off objects. By determining the time it (16) for the echoes to return to the radar set，a trained technician (17) determine the distance between the radar set and other objects. The word“radar”， (18) ，gets its name from the term“radio detection and ranging. ”“Ranging”is the term for detection of the (19) between an object and the radar set. Besides being of critical importance to pilot，radar is (20) for air traffic control，for tracking ships at sea，and for tracking weather systems and storms.
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Passage ThreeQuestions 31 to 35 are based on the following passage. An understanding of man’s effect on the balance of nature is crucial(关键的)to being able to find the appropriate remedial action. It is a very common belief that the problems of the population explosion are caused mainly by poor people living in poor countries who do not know enough to limit their reproduction. This is not true. The actual number of people in an area is not as important as the effect they have on nature. Developing countries do have an effect on their environment，but it is the populations of richer countries that have a far greater impact on the earth as a whole. For example，tropical forests are known to be essential to the balance of nature，yet we are destroying them at a great rate. They are being cleared not to benefit the natives of that country，but to satisfy the needs of rich countries. Central American forests are being destroyed for grassland to make pet food in the United States cheaper；in Papua New Guinea，forests are destroyed to supply cheaper cardboard packaging for Japanese electronic products；in Burma and Thailand，forests have been destroyed to produce mole attractive furniture in Singapore and Hong Kong. Therefore，a rich person living thousands of miles away may cause more tropical forest destruction than a poor person living in the forest itself. In short，it is everybody’s duty to safeguard the future of mankind-not only through population control，but by being more aware of the effect his actions have on nature. Nature is both fragile and powerful. It is very easily destroyed；on the other hand，it can easily destroy its most dangerous enemy-man. The purpose of the second paragraph is mainly to illustrate______.
Rifts were already opening up in the G20 as China hit out at Britain and the US for demanding that China boost its imports of foreign goods. A senior official from the People’s Republic said it was not appropriate in a "market economy" for a minister to call for a foreign nation to buy more of its products. Speaking at a briefing to reporters, Yu Jianhua of the Ministry of Commerce also described his country as "the biggest victim of protectionism" by other countries. "China has all along been making tremendous efforts to maintain a basic balance between exports and imports," he said. His remarks, made ahead of yesterday’s summit meeting, underlined the yawning divisions that remain between world leaders despite pledges of a "global compact" in Pittsburgh. Western powers like the UK and the US want China to bolster its domestic demand and increase imports as part of a "rebalancing" of the world economy. They warn American consumers can no longer remain the primary engines of global demand as they bolster savings and repay debts. Leaders have agreed to boost the status of the G20 and increase the International Monetary Fund representation of China, India and other developing countries as part of the shift to more sustainable patterns of global growth. However, achieving a consensus on a way forward will be extremely difficult—not least because global bodies will still have no ability to dictate economic policy to members. Chancellor Alistair Darling said yesterday: "This does not mean we are in a new world order where we have a G20 that tells everyone what to do. It is up to each country to decide what is best for them. " On financial reform, yesterday’s G20 deal will see restrictions on bonus payments and requirements forcing banks to hold more capital. Watchdogs will be able to limit payouts to a maximum share of a bank’s revenue if it is necessary to strengthen the firm’s finances. This stops far short of what French president Nicolas Sarkozy and other European leaders were seeking—a set monetary limit. Speaking during Saturday’s meetings, Mr Brown, the British prime minister, said : "The whole world community across the board is united in wanting to bring in rules and standards which will stamp out the bad practices of the past. " Complete the following sentences with information given in the passage in a maximum of 10 words for each sentence. It is extremely difficult for the G20 nations to achieve a consensus because global bodies it has have no ability to______.
I applied to a leading business school and have been called for an interview but I am getting cold feet. (76) If I get in, I would have to leave my job (safe, if a bit dull), would pay a fee of ￡45,000, and after a year and a half would emerge with no guarantee of another job. Is this one of the worst returns on investment going Or is it worth it for what I would learn and for the career boost and the likelihood that the economy will be better when I graduate Professional, female, 31
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