(B)

For years scientists have been worried about the effects of air pollution on the earth’s natural conditions. Some believe the air inside many houses may be more dangerous than the air outside.

Most scientists agree that every modern house has some kind of indoor pollution. People began to notice the problem in the early 1970s. When builders began making houses and offices, they didn’t want to waste energy. To do this they built buildings that limited the flow of air between inside and outside. They also used man-made building materials which are now known to let out harmful gases.

As the problem became more serious, scientists began searching for a way to deal with it. They discovered a natural pollution control system(系统) for building green plants.

Scientists believe that a plant’s leaves absorb the pollutants(污染物). In exchange(交换) the plant lets out oxygen(氧气) through its leaves. Studies of different plants show that each absorbs different chemicals. So the most effective(有效的) way to clean the air is to plant different kinds of plants.

(  ) 31. Indoor air pollution may be more dangerous than the air outside mainly because    .

A. the flow of air indoor is limited           B. the buildings are too high

C. people don’t want to waste energy      D. the building materials are harmful

(  ) 32. Some kind of indoor pollution can be found in     according to the passage.

A. all kinds of offices                 B. all kinds of houses

C. every modern house                D. every old house

(  ) 33. In the last paragraph the word “absorb” may mean    .

A. give out          B. take away      C. take in           D. turn into

(  ) 34. Scientists believe that plants can    .

A. absorb pollutants and let out oxygen     B. make your houses more beautiful

C. absorb all the pollutants             D. change pollutants into oxygen

(  ) 35. According to the last paragraph, we should     to clean the air.

A. plant some kinds of plants            B. have different kinds of plants

C. have the same kind of plant           D. plant fewer trees

(A)

 A kind of little cars may take the place of today’s big ones many years later. If everyone drives such cars in the future, there will be less pollution in the air. There will also be more space for parking cars in cities, and the streets will be less crowded.

The little cars of the future will cost less. Driving will be safer, too, as these little cars can go only 65 kilometers an hour. The cars of the future will be fine for going around a city, but they’ll not be useful for a long way. Little cars will go 450 kilometers before they need to stop for more gasoline(汽油). If big cars are still used with the small ones, two kinds of roads will be needed in the future. Some roads will be needed for the big, faster cars and other roads will be needed for the small, slower ones.

(  ) 26. There’s much pollution in the air today because    .

A. people drive big cars  

B. people drive little cars

C. small cars will go 450 kilometers before they need to stop for more gasoline

D. the usual size of cars today is too small

(  ) 27. The usual size of cars today is    .

A. much smaller than the future ones          B. as big as the future ones

C. as small as the future ones               D. bigger than the future ones

(  ) 28. Which of the following statements(叙述) is NOT TRUE?

A. Big cars cost more.

B. Big cars aren’t useful for a long way.

C. The cars of the future will be smaller than today’s cars.

D. Small cars are slower than big ones.

(  ) 29. The streets will be less crowded because    .

A. there will be fewer cars in the future

B. there will be fewer people in the streets

C. three kinds of roads will be built

D. future cars will be smaller

(  ) 30. Two kinds of roads will be needed in the future because    .

A. there will be too many cars in the future

B. more and more people will go to cities

C. big cars run faster and little cars run slower

D. it looks more beautiful to have two kinds of roads 

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