问题 不定项选择

分子间的距离为r0时,分子间的引力与斥力平衡,下列关于分子势能的说法中正确的是 [ ]

A.当分子间距离为r0时,分子势能最大,距离增大或减小,分子势能都减小

B.当分子间距为r0时,分子势能最小,距离增大或减小,分子势能都增大

C.当分子间距离大于分子直径10倍时,分子间相互作用力为0;分子间距离为r0时,分子间相互作用力的合力为零,因此,两个位置的分子势能相等

D.分子间距离越大,分子势能也越大

答案

答案:B

单项选择题
阅读理解

Three years ago, five parrots were set free in a wild place of Arizona, thousands of miles from the Channel Islands in Jersey where they had been looked after by zookeepers. No evolutionary strategies informed them how to behave in this new landscape of mountainous pine forest unoccupied by their kind for 50 years. To the researchers’ surprise, they failed to make contact with a group of wild parrots imported from Mexico and set free at the same time. Within 24 hours the reintroducing ended in failure, and the poor birds were back in cages, on their way to the safety of the Arizona reintroduction programme.

Ever since then, the programme has enjoyed great success, mainly because the birds now being set free are Mexican birds illegally caught in the wild, confiscated (没收) on arrival north of the border, and raised by their parents in the safety of the programme. The experience shows how little we know about the behaviour and psychology (心理) of parrots, as Peter Bennett, a bird researcher, points out: “Reintroducing species of high intelligence like parrots is a lot more difficult. People like parrots, always treating them as nothing more than pets or valuable ‘collectables’.”

Now that many species of parrot are in immediate danger of dying out, biologists are working together to study the natural history and the behaviour of this family of birds. Last year was an important turning point: conservationists founded the World Parrot Trust, based at Hayle in Cornwall, to support research into both wild and caged birds.

Research on parrots is vital for two reasons. First, as the Arizona programme showed, when reintroducing parrots to the wild, we need to be aware of what the birds must know if they are to survive in their natural home. We also need to learn more about the needs of parrots kept as pets, particularly as the Trust’s campaign does not attempt to discourage the practice, but rather urges people who buy parrots as pets to choose birds raised by humans.

小题1:What do we know about the area where the five parrots were reintroduced?

A.Its landscape is new to parrots of their kind.

B.It used to be home to parrots of their kind.

C.It is close to where they had been kept.

D.Pine trees were planted to attract birds.小题2:The reintroducing experience three years ago shows that man-raised parrots

A.can find their way back home in Jersey

B.are unable to recognize their parents

C.are unable to adapt to the wild

D.can produce a new species小题3:Why are researches on parrots important according to the passage?

A.The Trust shows great concern for the programme.

B.We need to know more about how to preserve parrots.

C.Many people are interested in collecting parrots.

D.Parrots’ intelligence may some day benefit people.小题4:According to the passage, people are advised ______.

A.to treat wild and caged parrots equally

B.to set up comfortable homes for parrots

C.not to keep wild parrots as pets

D.not to let more parrots go to the wild