单选题How can we get rid of garbage.9 Do we have enough energy sources to meet our future energy needs? These are two important questions that many people are asking today. Some people think that man might be able to solve both problems at the same time. They suggest using garbage as an energy source, and at the time it can save the land to hold garbage. For a long time, people buried garbage or dumped it on empty land. Now, empty land is scarce. But more and more garbage is produced each year. However, garbage can be a good fuel to use. The things in garbage do not look like coal, petroleum, or natural gas; but they are chemically similar to these fossil fuels. As we use up our fossil-fuel supplies, we might be able to use garbage as an energy source. Burning garbage is not a new idea. Some cities in Europe and the United States have been burning garbage for years. The heat that is produced by burning garbage is used to boil water. The steam that is produced is used to make electricity or to heat nearby buildings. In Paris, France, some power plants burn almost 2 million metric tons of the cities garbage each year. The amount of energy produced is about the same as would be produced by burning almost a half million barrels of oil. Our fossil fuel supplies are limited. Burning garbage might be one kind of energy source that we can use to help meet our energy needs.

单选题{{B}}21-25{{/B}} As people continue to grow and age, our body systems continue to change. At a certain point in your life your body systems will begin to weaken. Your joints may become stiff. It may become more difficult for you to see and bear. The slow change of aging causes our bodies to lose some of their ability to bounce back from disease and injury. In order to live longer, we have always tried to slow or stop this process that leads us toward the end of our lives. Many factors contribute to your health. A well-balanced diet plays an important role. The amount and type of exercise you get is another factor. Your living environment and the amount of stress you are under is yet another. But scientists studying senescence (衰老) want to know: Why do people grow old? They hope that by examining the aging process on a cellular level medical science may be able to extend the length of life.

单选题In 1999 when MiShel and Carl Meissner decided to have children, they tackled the next big issue: Should they try to have a girl? It was no small matter. MiShel"s brother had become blind from a hereditary condition in his early 20s, and the Meissners had learned that the condition is a disorder passed from mothers to sons. If they had a boy, he would have a 50 per cent chance of having the condition. A girl would be unaffected. The British couple"s inquiries about sex selection led them to Virginia, US, where a new sperm-separation technique, called MicroSort, was experimental at the time. When MiShel became pregnant she gave birth to a daughter. Now they will try to have a second daughter using the same technique. The technique separates sperm into two groups—those that carry the X-chromosome (染色体) producing a female baby and those that carry the Y-chromosome producing a male baby. The technology was developed in 1990s, but the opening of a laboratory in January 2003 in California marked the company"s first expansion. "We believe the number of people who want this technology is greater than those who have access to it," said Keith L. Blauer, the company"s clinical director. This is not only a seemingly effective way to select a child"s gender. It also brings a host of ethical (伦理的) and practical considerations—especially for the majority of families who use the technique for nonmedical reasons. The clinic offers sex selection for two purposes: to help couples avoid passing on a sex-linked genetic disease and to allow those who already have a child to "balance" their family by having a baby of the opposite sex. Blauer said the company has had an impressive success rate: 91 per cent of the women who become pregnant after sorting for a girl are successful, while 76 per cent who sort for a boy and get pregnant are successful. The technique separates sperm based on the fact that the X chromosome is larger than the Y chromosome. A machine is used to distinguish the size differences and sort the sperm accordingly.

单选题It was ______ who wrote those words on the blackboard． A．he B．him C．himself D．his

单选题In the muted cloth market, the shop-keepers speak in slow, ______tones, and the buyers follow suit.

单选题______ allowing the apples to go bad, Mr. Black sold them at half price.

单选题I broke my relationship with John because he always found ______ with me. A. error B. mistake C. fault D. failure

单选题I can"t possibly mark your homework: your handwriting is ______. You must spend some time in improving it.

单选题If your ______lively pets become passive, they might be ill.

单选题Although Kerry has had no formal education, he is one of the ______ businessmen in the company. A. alertest B. sternest C. nastiest D. shrewdest

单选题______yourbook,anddothisworkfirst.Youmayreaditlater.

单选题In a move to disseminate faculty research and scholarship more broadly, the Faculty of Arts and Sciences (FAS) voted on Tuesday to give Harvard University a worldwide license to make each faculty member's scholarly articles available and to exercise the copyright in the articles, (21) that the articles are not sold for a profit. "The goal of university research is the creation, dissemination, and (22) of knowledge. At Harvard, (23) so much of our research is of global significance, we have an essential responsibility to (24) the fruits of our scholarship as widely as possible," said Provost Steven E. Hyman. "Today's (25) in FAS will promote free and open (26) to significant, ongoing research. " Harvard will take advantage of the (27) by hosting FAS faculty members' scholarly articles in an open-access repository, making them available worldwide for (28) . The faculty member will (29) the copyright of the article, (30) the University's license. The repository contents can be made widely available to the (31) through search engines such as Google Scholar. This access will benefit scholars at all research (32) , which have seen their ability to (33) subscriptions to a full (34) of scholarly journals seriously compromised over the past few years. Research centers in poorer countries have been especially (35) by the access limitations caused by the high cost of many journals, Shieber pointed out.

单选题There are different ______ in the pond.

单选题The main objective reason is that some developed countries______from the basic principle of anti-dumping and take the Anti-dumping Law as a tool for trade protection.

单选题The news of the air crash was reported right away, but the______were not disclosed.

单选题"Does your family call you very often?" "Yes, my mother calls about once a week and ."______.

单选题Young drivers under 25 have the highest number of accidents while those over 50 have______.

单选题{{B}}练习六{{/B}} As a medium of exchange, money permits the separation of exchange into the two distinct acts of buying and selling, without requiring the seller to purchase goods from the person who buys his products, or vice versa. Hence producers who know they will be paid in money, can concentrate on finding the most suitable outlet (销路) for their goods, while buyers who will pay in money, can concentrate on finding the cheapest market for the things they wish to purchase. Specialization, which is vital to an advanced economy, is encouraged, because people whose output is not a complete product but only a part of one in which many others are involved can be paid an amount equivalent to their share of the product. Another advantage of money is that it is a measure of value—that is, it serves as a unit in terms of which the relative values of different products can be expressed. In a barter economy it would be necessary to determine how many plates were worth one hundred weight of cotton, or how many pens should be exchanged for a ton of coal, which would be a difficult and time-consuming (费时的) task. The process of establishing relative values would have to be undertaken for every act of exchange, according to what products were being offered against one another, and according to the two parties' desires and preferences. If I am trying to barter fish for bananas, for example, a lot would depend on whether the person willing to exchange bananas is or is not keen on fish. Thirdly, money acts as a store of wealth. It is difficult to imagine saving under a barter system. No one engaged on only one stage in the manufacture of a product could save part of his output, since he would be producing nothing complete. Even when a person actually produced a complete product the difficulties would be overwhelming. Most products deteriorate fairly rapidly, either physically or in value, as a result of long storage; even if storage were possible, the practice of storing products for years on end would involve obvious disadvantages—imagine a coal-miner attempting to save enough coal, which of course is his product, to keep him for life. If wealth could not be saved, or only with great difficulty, future needs could not be provided for, or capital accumulated to raise productivity.

单选题A. glance B. goal C. graceful D. technology