阅读理解。

    Some people think we have too much dirty air in large cities. Some of the dirty air is from cars. The more

cars there are in cities, the more dirty air we will have. Some people think we may go to work by bike,

because no dirty air is from bikes. The more people go to work by bike, the fewer cars there will be in cities.

So the dirty air will not be much. Do you think it is a good idea?

1．Some people think we have ______ in cities. [ ]

A. too much air

B. too much dirty air

C. too much clean air

D. too much dirty water

2．______ the dirty air is from cars. [ ]

A. Most of

B. All of

C. Some of

D. Many of

3．If we go to work ______, there will not be so much dirty air in cities. [ ]

A. by car

B. by bus

C. by air

D. by bike

4．The more cars there are in cities, ______ we will have. [ ]

A. the more clean air

B. the less dirty air

C. the more dirty air

D. the dirty air

5．The writer thinks that we should ______. [ ]

A. don't go to work

B. go to work by bike

C. stay at home

D. go to work by car