单选题In our own galaxy, the Milky Way, there are perhaps 200 billion stars, a small part of them probably have planets on which life is feasible. A. a small fraction in which B. a small fraction of which C. a small fraction which D. which a fraction of

单选题Employees in chemical factories are entitled to receive extra pay for doing hazardous work.

单选题Since arriving in New York, Thomas has had over 15 job interviews. And this is opportunity to be lost.

单选题 Few creatures on earth are as cute as the black lion tamarin, and few have as dramatic a story line. Pug-nosed and diminutive, with a comic fringe of hair, these monkeys dwell in trees in small tracts of forest in southeastern Brazil. Or they did until 1905, when they were declared extinct. No one saw a black lion tamarin again in the wild until 1970. Later, in the 1990s, some Brazilian researchers turned up a small set of isolated, inbred populations scattered over a wide region. Since that time, they have been engineering tamarin migration, doing everything they can to save the world's most distinctive primates. Although they are no larger than house cats, tamarins have brains big for their size and a family life organized like our own. They live in groups anchored by an adult male andadult female, along with their offspring. When a mother bears young, she usually produces twins, and although members of the group share in their upbringing, it is most often the father who carries them around in the trees, where the families feed on fruits, insects and bird's eggs. Unhappily for the lion tamarins, their tree-bound niche began to disappear after the Portuguese landed in Brazil and began clearing forest to make room for Rio de Janeiro, the settlements and farms. As is the case for so many threatened species, the breakup of their habitat sounded the death knell for tamarins, depriving them of the continuity of forest they require to remain abundant and safe from potential threats in any single vicinity. The animals avoid predators by hardly ever coming down from the trees, so even a narrow logging road through a forest can begin the breakup by preventing them from moving from one patch of forest to another. A simple solution was to build bridges across roads, allowing the monkeys to move from one forest to another. With some lumber and the researchers' work, habitats that had been separated became continuous again, improving opportunities for migrating and mating. The next step was to broaden the distribution of the population. The researchers captured two families of black lion tamarins and moved them to a new forest. After a year, the moves were declared a success: Not only had 80 percent of the tamarins survived, but they had also produced new offspring. So far, so good. The researchers had learned the animals could adjust to the new habitats, even if the insects there tasted a little different or the trees were a slightly different size. The techniques for saving species in the wild vary. Species with less stringent habitat requirements, like wild turkeys, have been rescued by moving them into new settings as well as outlawing their killing. More challenging to preserve are species that require a lot of land, like elephants, and species that have highly specific requirements for habitat and prey -- like black-footed ferrets. Ultimately, as in all challenges, knowledge is power to save wild species from extinction.

单选题He felt insulted at the comment that his writing was all______.

单选题When an organism is completely encapsulated and preserved, it becomes a fossil, therefore turning into evidence of things that once lived.

单选题It's terribly hot in the office; we're going to have an air-conditioner ______ tomorrow.

单选题I promise never to get drunk______．

单选题He based his holiday plans on the______that his girlfriend was coming with him.

单选题He______to return earlier than 3 o'clock.

单选题Even at an early stage the school felt that she ______ a good chance of passing her exams. A. stood B. gained C. possessed D. took

单选题Language learning usually ______ conscious imitation.

单选题Although we don't feel satisfied with the election results, we have to become reconciled ______the decision made by our fellow countrymen.

单选题He was frightened by______lightning. A．bolt of B．a piece of C．a flash of D．a

单选题He masked his fear by a show of confidence. A. demonstrated B. betrayed C. put up with D. concealed

单选题American Indian languages, which differ widely, tended to group many units of meaning into multisyllabic words. A. all tend B. and tend C. to tend D. tending

单选题Erosion that is a slow process, but it constantly changes the features on the surface of the earth.

单选题Corporations and labor unions have______great benefits upon their employees and members as well as upon the general publiC．

单选题When ______ at the door, she was given a warm welcome.

单选题I cannot thank you very much for your kindness, I owe my success to you.