单选题Egypt felled by Famine Even ancient Egypt's mighty pyramid builders were powerless in the face of the famine that helped bring down their civilization around 2180 BC．Now evidence gleaned from mud deposited by the River Nile suggests that a shift in climate thousands of kilometers to the south was ultimately to blame-and the same or worse could happen today. The ancient Egyptians depended on the Nile's annual floods to irrigate their crops. But any change in climate that pushed the African monsoons southwards out of Ethiopia would have been diminished these floods. Dwindling rains in the Ethiopian highlands would have meant fewer plants to stablise the soil. When rain did fail it would have washed large amounts of soil into the Blue Nile and into Egypt, along with sediment from the White Nile. The Blue Nile mud has a different isotope signature from that of the White Nile. So by analyzing isotope differences in mud deposited in the Nile Delta, Michael Krom of Leeds University worked out what proportion of sediment came from each branch of the river. Krom reasons that during periods of drought, the amount of the Blue Nile mud in the river would be relatively high. He found that one of these periods, from 4500 to 4200 years ago, immediately predates the fall of the Egypt's Old Kingdom. The weakened waters would have been catastrophic for the Egyptians. "Changes that affect food supply don't have to be very large to have a ripple effect in societies, " says Bill Ryan of the Lamont Doherty Earth Observatory in New York. Similar events today could be even more devastating, says team member Daniel Stanley, a geoarchaeologist from the Smithsonian Institution in Washington, D. C. "anything humans do to shift the climate belts would have an even worse effect along the Nile system today because the populations have increased dramatically. /

单选题 Cost as a Factor in Supply In a purely competitive market, the supplier of goods and services has no control over the market price, because he produces too little to influence market conditions. With no difference between his products and the products (51) his competitors, he will sell nothing if he charges above the market price and he will sell all if he charges at or (52) the market price. However, in considering the price, he must take the (53) of production into consideration. There are times when he may be willing to sell below his cost. This might happen when prices tumble for (54) he believes will be a short time. However, no business person can (55) to lose money for a prolonged period. He must be constantly (56) of his costs in relation to the market price if he is to compete successfully and earn a profit. Many people have the impression that as production increases, costs per unit decrease. (57) mass production has made this true in certain industries and at certain levels of production, (58) logic and practical experiences have shown that costs per unit begin to rise beyond a certain level of production. Some economists (59) to this principle as the law of increasing costs. The reason costs rise as production goes up is (60) . However, it is easy to recognize that as production goes up, the need for additional factors of production will also grow, (61) competitive bidding in the marketplace for the factors of production. If a producer needs (62) skilled labor to produce more, and none of this labor is unemployed, the producer will have to get (63) from other sources. This can be done by (64) higher wages. Higher bidding would also apply to the other factors of production. We must also recognize that not all labor is equally productive, (65) not all land is equally fertile and not all ore (矿石) is equally rich in the mineral wanted.

单选题He {{U}}achieved{{/U}} success through hard work. A. reached B. arrived C. attained D. took

单选题Because of gambling, his debt has amounted to 20,000 dollars.A. reachedB. lostC. arrivedD. rose

单选题Which of the followings can best replace the title of the passage?

单选题Long skirts have come into fashion again. Faded jeans are still in fashion too.

单选题She eventually married the most persistent one of her admirers. A. in a way B. in due course C. in the end D. in any case

单选题She will be pleased to meet you.

单选题You should cultivate the habit of reading carefully.

单选题Saving Money Where you save your money often depends on what you are saving for. If you are saving to buy a dictionary or to go to a concert, then probably keep your money somewhere in your room. If you are saving for a big purchase like a mountain bike or a school trip, where would you save your money? One place to save money is the bank. Putting your money in a savings account wilt help your money earn more money. If you put your money in a piggy bank (猪形储蓄罐), one year later you"ll still have the same amount of money you put in. If you put your money in a savings account, one year later, you"ll have more money. than you put in. Why? When you keep your money in a bank, your money earns interest. Interest is the amount of money a bank pays you to use your money. The bank uses your money (and the money of other people, too) to loan money to people and businesses. The bank will send you a statement several times a year. A bank statement tells you how much money there is in your account. It also tells you how much interest you have earned. If you leave your money in the bank, you can watch it grow! Another way you can save money is to buy a certificate of deposit or CD. If you have some money that you don"t need to use for a long time, this is a good way to make your money grow. You can buy a CD at a bank. You agree not to use the money for a certain period of time. That period might be from six months to five years. You can"t touch your money during that time. If you do, you must pay a penalty, or fee. Since the bank is using your money for that time period, it will pay you interest. You will earn more interest with a CD than in a savings account. Can you guess why? It"s because you promise to leave your money in the bank for a certain period of time. Banks pay different rates of interest. So, you may want to compare rates in newspaper ads before buying a CD.

单选题The secretary is expected to Uexplore/U ideas for post-war reconstruction of the area.

单选题Many tourists are attracted to the New England states by the autumn {{U}}foliage{{/U}}.

单选题They have Ugiven up/U the hope to save their friend from drowning.

单选题The Science of Persuasion If leadership consists of getting things done through others, then persuasion is one of the leader"s essential tools. Many executives have assumed that this tool is beyond their grasp, available only to the charismatic (有魅力的) and the eloquent. Over the past several decades, though, experimental psychologists have learned which methods reliably lead people to concede, comply, or change. Their research shows that persuasion is governed by several principles that can be taught and applied. The first principle is that people are more likely to follow someone who is similar to them than someone who is not. Wise managers, then, ask peers to help make their cases. Second, people are more willing to cooperate with those who are not only like them but who like them, as well. So it"s worth the time to uncover real similarities and offer genuine praise. Third, experiments confirm the intuitive truth that people tend to treat you the way you treat them. It"s sound policy to do a favor before seeking one. Fourth, individuals are more likely to keep promises they make voluntarily and clearly. The message for managers here is to get commitments in writing. Fifth, studies show that people really do defer to (服从) experts. So before they attempt to exert influence, executives should take pains to establish their own expertise and not assume that it"s self-evident. Finally, people want more of a commodity when it"s scarce; it follows, then, that exclusive information is more persuasive than widely available data.

单选题Throughout most of their lives,human beings perpetually learn and increase their mental capacities. A．actually B．readily C．finally D．constantly

单选题From my standpoint , you know, this thing is just funny.

单选题I propose that we discussed this at the next meeting.

单选题The secretary is expected to explore ideas for post-war reconstruction of the area.

单选题I shall never forget the look of intense anguish on the face of his parents when they heard the news.

单选题 Ford Abandons Electric Vehicles The Ford motor company's abandonment of electric cars effectively signals the end of the road for the technology, analysts say. General Motors and Honda ceased production of battery-powered cars in 1999, to focus on fuel cell and hybrid electric gasoline engines, which are more attractive to the consumers. Ford has now announced it will do the same. Three years ago, the company introduced the Think City two-seater car and a golf cart called the THINK, or Think Neighbor. It hoped to sell 5,000 cars each year and 10,000 carts. But a lack of demand means only about 1,000 of the cars have been produced, and less than 1,700 carts have been sold so far in 2002. "The bottom line is we don't believe that this is the future of environment transport for the mass market," Tim Holmes of Ford Europe said on Friday. "We feel we have given electric our best shot." The Think City has a range of only about 53 miles and up to a six-hour battery recharge time. General Motors' EVI electric vehicle also had a limited range of about 100 miles. The very expensive batteries also mean electric cars cost much more than petrol-powered alternatives. An electric Toyota RAV4 EV vehicle costs over $42,000 in the US. compared with just $17,000 for the petrol version. Toyota and Nissan are now the only major automanufacturers to produce electric vehicles. "There is a feeling that battery electric has been given its chance. Ford now has to move on with its hybrid program, and that is what we will be judging them on," Roger Higman, a senior transport campaigner at UK Friends of the Earth, told the Environment News Service. Hybrid cars introduced by Toyota and Honda in the past few years have sold well. Hybrid engines offer greater mileage than petrol—only engines, and the batteries recharge themselves. Ford says it thinks such vehicles will help it meet planned new guidelines "on vehicle emissions" in the US. However, it is not yet clear exactly what those guidelines will permit. In June, General Motors and Daimler Chrysler won a court injunction, delaying by two years Californian legislation requiring car-makers to offer 100,000 zero-emission and other low-emission vehicles in the state by 2003. Car manufacturers hope the legislation will be rewritten to allow for more low-emission, rather than zero-emission, vehicles.