单选题In English learning, a ______ cycle occurs when a student makes more errors after being scolded.

单选题Experienced baseball fielders can tell how far a ball is going to travel just by listening to the crack of the bat. If they didn't, they wouldn't stand a chance of catching it, claims a physicist in New York. "When a baseball is hit straight at an outfielder, he cannot quickly judge the angle of the scent and the distance the ball will travel," says Robert Adair, a physicist at Yale University. If he relied purely upon visual information, the fielder would have to wait for about one-and-a-half seconds before he could tell accurately if the pitcher hit the ball long or short. By this time the ball may have travelled too far for him to reach it in time. To stand a fighting chance of catching it, according to Adair, fielders must listen to the sound the ball hitting the bat to judge how far it will travel. There is anecdotal evidence to support this, he says. A former centre fielder told Adair: "If I heard a crack I ran out, if I heard a clunk, I ran in." To test his hypothesis, Adair calculated how quickly a fielder could change direction if he had misjudged whether the ball was going long or short. The difference between the "crack" and "clunk” can he explained by how well the batter has hit the ball, and could mean a difference in running distance of as much as 30 metres, he told delegates at a meeting of the Acoustical Society of America in Chicago last week. Scientists already knew that to hit a ball long the batter must strike it somewhere near the vibrational node of the bat, known as the sweet spot. Balls hit on the sweet spot generate fewer energy-sapping vibrations in the bat, allowing greater energy transfer to the ball. Conversely, mishit balls make the bat vibrate strongly and so do not travel as far. Adair is quick to point out that this only applies to wooden bats, which are used in major league baseball. Aluminum bats, on the other hand, tend to produce a fairly uniform "ping” sound regardless of where you hit them.

单选题He's ______ his children to my care for a day.

单选题The view over a valley of a tiny village with thatched (草盖的) roof around a church; a drive through a narrow village street lined with thatched cottages painted pink or white; the sight over the rolling hills of a pretty collection of thatched farm buildings—these are still common sights in parts of England. Most people will agree that the thatched roof is an essential part of the attraction of the English countryside. Thatching is in fact the oldest of all the building crafts practiced in the British Isles (英伦诸岛). Although thatch has always been used for cottage and farm buildings, it was once used for castles and churches, too. Thatching is a solitary (独自的) craft, which often runs in families. The craft of thatching as it is practiced today has changed very little since the Middle Ages. Over 800 full-time thatches are employed in England and Wales today, maintaining and renewing the old rods as well as thatching newer houses. Many property owners choose thatch not only for its beauty but became they know it will keep them cool in summer and warm in winter. In fact, if we look at developing countries, over half the world lives under thatch, but they all do it in different ways. People in developing countries are often reluctant to go back to traditional materials and would prefer modern buildings. However, they may lack the money to allow them to import the necessary materials. Their temporary mud huts with thatched roofs of wild grasses often only last six months. Thatch which has been done the British way lasts from twenty to sixty years, and is an effective defense against the heat.

单选题Most engineers were ______ about the effectiveness of the new model of word-processors.

单选题Some experts fear that these regulations will be so strict as to Uparalyze/U economic activities.

单选题American children {{U}}customarily{{/U}} go trick-or-treating on Halloween.

单选题Thousands of people who have no relevant ______ or business are put into important jobs.

单选题Even though the investigation has been going on for two months, the police have ______no further details about the accident.

单选题Man: I've figured it all out. It looks like it'll take us about 5 hours to drive from here to Chicago. Woman: It'd be more relaxing to take the train. But I guess we should watch our expenses. Question: What does the woman imply?

单选题What's a label worth? A lot, it seems, when it comes to towels in a New York shop. Two Harvard University researchers, Michael Hiscox and Nicholas Smyth conducted an experiment on two sets of towels. One lot carried a label with the logo "Fair and Square" and the following message: These towels have been made under fair labor conditions, in a safe and healthy working environment which is free of discrimination, and where management has committed to respecting the rights and dignity of workers. The other set had no such label. Over five months, the researchers observed the impact of making various changes such as switching the label to the other set of towels and raising prices. The results were striking: not only did sales of towels increase when they carried the Fair and Square label, they carried on increasing each time the price was raised. No wonder companies are keen to appeal to ethically minded consumers, whether on labor standards or green credentials. On greenery, British consumers are divided into four broad groups. About one in ten is passionately green and will go out of their way to shop accordingly. At the other end of the spectrum one-quarter are not interested. In-between are those who care but want green consumption to be easy, and those who are vaguely concerned but don't see how they can make a difference. That represents an opportunity: three-quarters of British consumers are interested in the green theme in some way. But even the keenest ethical consumer faces complicated trade-offs, and sometimes the apparently obvious ethical choice turns out to be the wrong one. Surely it must be greener for Britons to buy roses from the Netherlands than ones air-freighted from Kenya? In fact, a study at Cranfield University showed the carbon footprint of the Dutch roses to be six times as large because they had to be grown in heated greenhouses. Consumers are right to be suspicious of the ethical claims made for many products. A recent study of the labels of 1 018 products in big stores in North America by TerraChoice, an environmental marketing agency, found that almost all of them were guilty of some form of "green washing". They did not tell outright lies, but nor did they tell the whole truth.

单选题Gerald was absolutely certain of its veracity.

单选题The computer will analyze the ______ data and give us a report.

单选题Man: Pam, I don't understand the problem. You've known for months this report was due today. Woman: I know... but I'm afraid I need another few days. The data was harder to interpret than I thought it would be. Question: What does the woman mean?

单选题The television station is supported by ______ from foundations and other sources

单选题This passage is probably a _____

单选题Important newspapers are supposed to carry authentic news reports and try to be informative.

单选题This college graduate tried our company a third time, ______ to be turned down again.

单选题The students were given complimentary passes for the new movie.

单选题Peter, (together with) his wife and (two sons), (are) to arrive (on the) evening flight.A. together withB. two sonsC. areD. on the