单选题Single mums are better at raising their kids than two parents—at least in the bird world. Mother zebra finches have to work harder and raise fewer chicks on their own, but they also produce more attractive sons who are more likely to get a mate. The finding shows that family conflict is as important an evolutionary driving force as ecological factors such as hunting and food supply. With two parents around, there's always a conflict of interests, which can have a detrimental effect on the quality of the offspring. In evolutionary terms, the best strategy for any parent in the animal world is to find someone else to care for their offspring, so they can concentrate on breeding again. So it's normal for parents to try to pass the buck to each other. But Ian Hartley from the University of Lancaster and his team wondered how families solve this conflict, and how the conflict itself affects the offspring. To find out, they measured how much effort zebra finch parents put into raising their babies. They compared single females with pairs, by monitoring the amount of food each parent collected, and removing or adding chicks so that each pair of birds was raising four chicks, and each single mum had two—supposedly the same amount of work. But single mums, they found, put in about 25 per cent more effort than females rearing with their mate. To avoid being exploited, mothers with a partner hold back from working too hard if the rather is being lazy, and it's the chicks that pay the price. "The offspring suffer some of the cost of this conflict," says Hartley. The cost does not show in any obvious decrease in size or weight, but in how attractive they arc to the opposite sex. When the chicks were mature, the researchers tested the "fitness" of the male offspring by offering females their choice of partner. Those males reared by single mums were chosen more often than those from two-parent families. Sexual conflict has long been thought to affect the quality of care given to offspring, says zoologist Rebecca Kilner at Cambridge University, who works on conflict of parents in birds. "But the experimental evidence is not great. The breakthrough here is showing it empirically." More surprising, says Kilner, is Hartley's statement that conflict may be a strong influence on the evolution of behaviour, clutch size and even appearance. "People have not really made that link," says Hartley. A female's reproductive strategy is usually thought to be affected by hunting and food supply. Kilner says conflict of parents should now be taken into account as well.

单选题{{B}}Directions:{{/B}}Read the following text. Choose the best word(s) for each numbered blank and mark A, B, C or D on ANSWER SHEET 1. Most plants can make their own food from sunlight,{{U}} (1) {{/U}}some have discovered that stealing is an easier way to live, Thousands of plant species get by{{U}} (2) {{/U}}photosynthesizing, and over 400 of these species seem to live by pilfering sugars from an underground{{U}} (3) {{/U}}of fungi(真菌). But in{{U}} (4) {{/U}}a handful of these plants has this modus operandi been traced to a relatively obscure fungus. To find out how{{U}} (5) {{/U}}are{{U}} (6) {{/U}}, mycologist Martin Bidartondo of the University of California at Berkeley and his team looked in their roots. What they found were{{U}} (7) {{/U}}of a common type of fungus, so{{U}} (8) {{/U}}that it is found in nearly 70 percent of all plants. The presence of this common fungus in these plants not only{{U}} (9) {{/U}}at how they survive, says Bidartondo, but also suggests that many ordinary plants might prosper from a little looting, too. Plants have{{U}} (10) {{/U}}relations to get what they need to survive. Normal,{{U}} (11) {{/U}}plants can make their own carbohydrates through photosynthesis, but they still need minerals. Most plants have{{U}} (12) {{/U}}a symbiotic relationship with a{{U}} (13) {{/U}}network of what are called mycorrhizal fungi, which lies beneath the forest{{U}} (14) {{/U}}. The fungi help green plants absorb minerals through their roots, and{{U}} (15) {{/U}}, the plants normally{{U}} (16) {{/U}}the fungi with sugars, or carbon. With a number of plants sharing the same fungal web, it was perhaps{{U}} (17) {{/U}}that a few cheaters—dubbed epiparasites—would evolve to beat the system.{{U}} (18) {{/U}}, these plants reversed the flow of carbon,{{U}} (19) {{/U}}it into their roots from the fungi{{U}} (20) {{/U}}releasing it as "payment."

单选题With the development of sophisticate instruments, earthquake will become predictable.

单选题{{B}}Passage Two{{/B}} A hundred years ago, the game we now call football did not exist. American football started during a game between two colleges. The teams had got together to play what they called "football", but each team played by different roles. One team played what we now call soccer. The other played what we now call rugby (橄榄球) . Both games had been invented a thousand years before. In the first kind of football game ever played, all the men from one village tried to kick a ball into another village. The men of the second village tried to kick the ball into the first. Hundreds of people joined in, running everywhere, running crops and knocking down fences. In time, people agreed on some rules to keep order, but many rules were left open to change. Different rules developed in different places. When the two colleges met to play football, each followed its own rules. They mixed the games together and invented a new game. A hundred years later we call that game American football. In what ways do you suppose the game we know now will have changed in another hundred years?

单选题Soybean meat is similar to real meat ______.

单选题Why is the program that's trying to save condors putting them into danger?

单选题How fit are your teeth? Are you lazy about brushing them? Never fear: An inventor is on the case. An electric toothbrush senses how long and how well you brush, and it lets you track your performance on your phone. The Kolibree toothbrush was exhibited at the International Consumer Electronics Show in Las Vegas this week. It senses how it is moved and can send the information to an Android phone or iPhone via a Bluetooth wireless connection. The toothbrush will be able to teach you to brush right (don't forget the insides of the teeth!) and make sure you're brushing long enough. "It's kind of like having a dentist actually watch your brushing on a day-to-day basis," says Thomas Serval, the French inventor. The toothbrush will also be able to talk to other applications on your phone, so developers could, for instance, create a game controlled by your toothbrush. You could score points for beating monsters among your teeth. "We try to make it smart but also fun," Serval says. Serval says he was inspired by his experience as a father. He would come home from work and ask his kids if they had brushed their teeth. They said "yes," but Serval would find their toothbrush heads dry. He decided he needed a brush that really told him how well his children brushed. The company says the Kolibree will go on sale this summer, for $ 99 to $ 199, depending on features. The U. S. is the first target market. Serval says that one day, it'll be possible to replace the brush on the handle with a brushing unit that also has a camera. The camera can even examine holes in your teeth while you brush.

单选题(According) to the graduate catalog, student housing (is) (more cheaper) (than) housing off campus.

单选题Britain is proud of her great poets; just as Italy is proud of her painters, and Germany ______of her composers.

单选题The word "Also" (line 2, para. 2) is used to ______.

单选题The influence of socialization process may

单选题It is not unusual for chief executives to collect millions of dollars a year in pay, stock options, and bonuses. In the last fifteen years, while executive remuneration rose, taxes in the highest income bosses went down. Millionaires are now common-place. Amiability is not a prerequisite for rising to the top, and there are a number of chief executive officers with legendary bad tempers. It is not the boss' job to worry about the well-being of his subordinates although the man with many enemies will be swept out more quickly in hard times; it is the company he worries about. His business savvy is supposed to be based on intimate knowledge of his company and the industry so he goes home nightly with a full briefcase. At the very top--and on the way up--executives are exceedingly dedicated. The American executive must be capable of enough small talk to get him through the, social part of his schedule, but he is probably not a highly cultured individual or an intellectual. Although his wife may be on the board of the symphony or opera, he himself" has little time for such pursuits. His reading may largely concern business and management, despite interests in other fields. Golf provides him with a sportive outlet that combines with some useful socializing. These days, he probably attempts some form of aerobic exercise to "keep the old heart in shape" and for the same reason goes easy on butter and alcohol, and substances thought to contribute to taking highly stressed executives out of the running. But his doctor's admonition to "take it easy" falls on deaf" ears. He likes to work. He knows there are younger men nipping at his heels. Corporate head-hunting, carried on by "executive search firms", is a growing industry. America has great faith in individual talent, and dynamic and aggressive executives are so in demand that companies regularly mid each other's managerial ranks.

单选题What is not covered in the service of ad B?

单选题Some writers who once greatly______the literary critic have recently recanted, substituting ______for their former criticism.

单选题It's impossible for parents to ______ their children from every danger.