单选题Don"t irritate her, she"s on a short fuse today.

单选题There are a limited number of books on this subject in the library. A. small B. total C. good D. great

单选题Almost all economists agree that nations gain by trading with one another. A. work B. profit C. rely D. prove

单选题She persevered in her ideas despite obvious objections raised by friends.

单选题There is {{U}}an abundant{{/U}} supply of cheap labor in this country. A.steady B.plentiful C.an extra D.a stable

单选题Everybody was glad to see Mary back A. sorry B. sad C. happy D. angry

单选题What factor can be attributed to German prosperity?

单选题Norman Blarney is an artist of deep {{U}}convictions{{/U}}. A. statements B. beliefs C. suggestions D. claims

单选题The rules are too {{U}}rigid{{/U}} to allow for human error. A. inflexible B. general C. complex D. direct

单选题The workers finally called off the strikes.

单选题Frank has always been loyal to his friends.A. friendlyB. faithfulC. hostileD. kind

单选题Ants Have Big Impact on Environment as "Ecosystem Engineers" Research by the University of Exeter has revealed that ants have a big impact on their local environment as a result of their activity as "ecosystem engineers" and predators. The study, published in the Journal of Animal Ecology, found that ants have two distinct effects on their local environment. Firstly, through moving of soil by nest building activity and by collecting food they affect the level of nutrients in the soil. This can indirectly impact the local populations of many animal groups, from decomposers to species much higher up the food chain. Secondly, they prey on a wide range of other animals, including larger prey which can be attacked by vast numbers of ant workers. Dirk Sanders, an author of the study from the university"s Centre for Ecology and Conservation, said: "Ants are very effective predators which thrive in huge numbers. They"re also very territorial and very aggressive, defending their resources and territory against other predators. All of this means they have a strong influence on their surrounding area." "In this research, we studied for the first time how big this impact is and the subtleties of it. What we found is that despite being predators, their presence can also lead to an increase in density and diversity of other animal groups4. They genuinely play a key role in the local environment, having a big influence on the grassland food web," Sanders said. The study, carried out in Germany, studied the impact of the presence of different combinations and densities of black garden ants and common red ants, both species which can be found across Europe, including in the UK. It found that a low density of ants in an area increased the diversity and density of other animals in the local area, particularly the density of herbivores and decomposers. At higher densities ants had no or the opposite effect, showing that predation is counteracting the positive influence. Dr Frank van Veen, another author on the study, said. "What we find is that the impact of ants on soil nutrient levels has a positive effect on animal groups at low levels, but as the number of ants increases, their predatory impacts have the bigger effect — thereby counteracting the positive influence via ecosystem engineering." Ants are important components of ecosystems not only because they constitute a great part of the animal biomass but also because they act as ecosystem engineers. Ant biodiversity6is incredibly high and these organisms are highly responsive to human impact, which obviously reduces its richness. However, it is not clear how such disturbance damages the maintenance of ant services to the ecosystem. Ants are important in below ground processes through the alteration of the physical and chemical environment and through their effects on plants, microorganisms, and other soil organisms.

单选题TV Games Shows One of the most fascinating things about television is the size of the audience. A novel can be on the "best sellers" list with a sale of fewer than 100,000 copies, but a popular TV show might have 70 million TV viewers. TV can make anything or anyone well known overnight. This is the principle behind "quiz" or "game" shows, which put ordinary people on TV to play a game for the prize and money. A quiz show can make anyone a star, and it can give away thousands of dollars just for fun. But all of this money can create problems. For instance, in the 1950s, quiz shows were very popular in the US and almost everyone watched them. Charles Van Doren, an English instructor, became rich and famous after winning money on several shows. He even had a career as a television personality. But one of the losers proved that Charles Van Doren was cheating. It turned out that the show's producers, who were pulling the strings, gave the answers to the most popular contestants beforehand. Why? Because if the audience didn't like the person who won the game, they turned the show off. Based on his story, a movie under the title "Quiz Show" is on 40 years later. Charles Van Doren is no longer involved with TV. But game shows are still here, though they aren't taken as seriously. In fact, some of them try to be as ridiculous as possible. There are shows that send strangers on vacation trips together, or that try to cause newly married couples to fight on TV, or that punish losers by humiliating them. The entertainment now is to see what people will do just to be on TV. People still win money, but the real prize is to be in front of an audience of millions.

单选题The Rising Oil Price Could the bad old days of economic decline be about to return? Since OPEC agreed to sup-ply-cuts in March, the price of crude oil has jumped to almost $ 26 a barrel, up from less than $10 last December. This near-tripling of oil prices calls up scary memories of the 1973 oil shocks resulted in double-digit inflation and global economic decline. So where are the headlines warning of gloom and doom this time? The oil price was given another push up this week when Iraq suspended oil exports. Strengthening economic growth, at the dame time as winter grips the northern hemisphere, could push the price higher still in the short term. Yet there are good reasons to expect the economic consequences now to be less severe than in the 1970s. In most countries the cost of crude oil now accounts for a smaller share of the price of petrol than it did in the 1970s. In Europe, taxes account for up to four-fifths of the retail price, so even quite big changes in the price of crude have a more muted effect on pump prices than in the past. Rich economics are also less dependent on oil than they were, and so less sensitive to swings in the oil price. Energy conservation, a shift to other fuels and a decline in the importance of heavy, energy-intensive industries have reduced oil consumption. Software, consultancy and mobile telephones use far less oil than steel or car production. For each dollar of GDP (in constant prices) rich economics now use nearly 50% less oil than in 1973. The OECD estimates in its latest Economic Outlook that, if oil prices averaged $ 22 a barrel for a full year, compared with $13 in 1998, this would increase the oil import bill in rich economies by only 0.25%～0.5% of GDP. That is less than one-quarter of the income loss in 1974 or 1980. On the other hand, oilimporting emerging economies—to which heavy industry has shifted— have become more energy-intensive, and so could be more seriously squeezed. One more reason not to lose sleep over the rise in oil prices is that, unlike the rises in the 1970s, it has not occurred against the background of general commodity-price inflation and global excess demand. A sizable portion of the world is only just emerging from economic decline. The Economist's commodity price index is broadly unchanging from a year ago. In 1973 commodity prices jumped by 70%, and in 1979 by almost 30%.

单选题A person who deals with the public must be courteous at all times, even when he or she is very tired.

单选题The moon and most artificial satellites travel around the Earth in elliptical paths .

单选题 On the Trial of the Honey Badger On a recent field trip to the Kalahari Desert, a team of researchers learn a lot more about honey badgers. The team employed a local wildlife expert Kitso Khama to help them locate and follow the badgers across the desert. Their main aim was to study the badgers' movements and behavior as discreetly (谨慎地) as possible without frightening them away or causing them to change their natural behavior. They also planned to trap a few and study them close up before releasing them in view of the animal's reputation, this was something that even Khama was reluctant to do. "The problem with honey badgers is they are naturally curious animals, especially when they see something new," he says. "That, combined with their unpredictable nature, can be a dangerous mixture. If they sense you have food, for example, they won't be shy about coming right up to you for something to eat. They're actually quite sociable creatures around humans, but as soon as they feel they might be in danger, they can become extremely vicious (凶恶的). Fortunately this is rare, but it does happen." The research confirmed many things that were already known. As expected, honey badgers ate any creatures they could catch and kill. Even poisonous snakes, feared and avoided by most other animals, were not safe from them. The researchers were surprised, however, by the animal's fondness for local melons, probably because of their high water content. Preciously researchers thought that the animal got all of its liquid requirements from its prey (猎物). The team also learnt that, contrary to previous research findings, the badgers occasionally formed loose family groups. They were also able to confirm certain results from previous research, including the fact that female badgers never socialized with each other. Following some of the male badgers was a challenge, since they can cover large distances in a short space of time. Some hunting territories cover more than 500 square kilometers. Although they seem happy to share these territories with other males, they are occasional fights over an important food source, and male badgers can be as aggressive towards each other as they are towards other species. As the badgers became accustomed to the presence of people, it gave the team the chance to get up close to them without being the subject of the animal's curiosity—or sudden aggression. The badgers' eating patterns, which had been disrupted, returned to normal. It also allowed the team to observe more closely some of the other creatures that form working associations with the honey badger, as these seemed to badgers' relaxed attitude when near humans.

单选题A lot of people could fall ill after drinking contaminated water.

单选题Such subjects are not within the scope of this book.

单选题The man in the comer admitted to ______ a lie to the manager of the company.A. toldB. tellC. tellingD. tells