Polar bears live mostly on __________ sea ice, which they use as __________ platform for hunting seals.

A. a; a      B. a; the      C. 不填; a      D. the; 不填

We first met on a train in 2000. We both felt immediately that we _________ each other for years.

A. knew  B. have known

C. had known        D. know

Most people think of zoos as safe heavens for animals, where problems such as difficulty finding food and avoiding predators (食肉動(dòng)物) don’t exist. Therefore, animals in zoos should live to a ripe old age.

But that may not be true for the largest land animals on earth. Scientists have known that elephants in zoos often suffer from poor health. They develop diseases and they are even unable to have babies.

To learn more about how captivity (圈養(yǎng)) affects elephants, a team of international scientists compared the lifespans (壽命) of the zoo-born elephants with the lifespans of thousands of wild elephants. They also compared some Asian elephants living in zoos with some Asian elephants which work in logging camp (伐木場(chǎng)), over almost the same time period.

The team found that elephants born in zoos lived an average of 16.9 years, but elephants that died of natural causes lived an average of 56 years. Asian elephants followed a similar pattern. In zoos, they lived 18.9 years, while those in the logging camp lived 41.7 years.

Scientists don’t yet know why wild elephants seem to live so much better than their zoo-raised counterparts (同類). Georgia Mason, a biologist at the University of Guelph in Canada, who led the study, thinks stress and obesity (肥胖) may be to blame. Zoo elephants don’t get the same kind of exercise they would in the wild. Elephants’ social lives are also much different in zoos than in the wild, where they live in large family groups.

Most people believe that________.

A. animals in zoos should live a longer life

B. zoos are not good for animals to live in

C. zoos are not suitable for large animals         

D. captivity can affect animals in many ways

The purpose of the international scientists is_________.

A. to compare the lifespans of different animals

B. to find out how captivity affects elephants

C. to learn the lifespans of male and female elephants

D. to compare the lifespans of elephants in different places

Which elephants live the longest according to the study?

A. Elephants born in zoos.             

B. Elephants that live in the wild.

C. Elephants that work in logging camps.   

D. Female Asian elephants in logging camps.

We can infer from the passage that_________.

A. elephants in zoos suffer less stress than those in the wild

B. elephants in zoos live an easy life

C. social lives are not important to elephants             

D. zoo life can be stressful to elephants

What are the advantages to elephants in the wild according to the passage?

A. They face fewer problems.            B. They can find food more easily.

C. They live in large social groups.  D. They are freer to move.  

When you come here for your holiday next time, don’t go to ______ hotel; I can find you ______ bed in my flat.

A. the; a B. the; 不填　　C. a; the D. a; 不填

The monument was built in honor of the explorer who was believed _____ the river.

A. to have discovered 　　    B. to have been discovered

C. to discover        　　       D. having been discovered

The crowd cheered wildly at the sight of liu xiang, who was reported _______ the world record in the 110-meter hurdle race.  

A. breaking       B. having broken       C. to have broken     D. to break

I’ll probably see you on Sunday； 　　　　， it will be on Monday.

A. thus          B. then              C. after all            D. if not

Hardly ____ into the country ____ it began to rain.

      A.  we had got; when                B. we got; than

      C.  had we got; when                D. did we get; than 

Soon they got to the bank,____stood a big pine tree.

     A. In front of which         B. There            C. Where       D. It

By using ears one can tell the direction ____ a sound comes.

     A. in which      B. from which       C. with which      D. through which