阅读理解

　　The dark smoke that comes out of stacks (烟囱) or from a burning dump (垃圾) contains tiny bits of solid or liquid matter. The smoke also contains many gases, most of which cannot be seen. Altogether, they make up the serious problems of air pollution. In so many places it keeps us from seeing the sun, irritates (刺激) our eyes, causes us to cough, and makes us ill.

　　Air pollution can spread from city to city. It even spreads from one country to another. Some northern European countries have had “black snow” from pollutants that have traveled through the air from other countries and have fallen with the snow. So, air pollution really is a global (全球性的)problem.

　　Air pollution can kill babies, older people, and those who have respiratory (呼吸的) diseases, In London, in 1952, four thousand people died in one week as a result of a serious air-pollution episode (一连串事件中的一个). In 1948, in the small town of Donora, Pennsylvania, twenty people died in a four-day period of bad air pollution.

　　At levels (平原) often found in cities, air pollution increases the risks of certain lung diseases, of course, smoking and other factors help to cause these illnesses, too, but these cases have increased greatly during recent years as air pollution has become worse.

　　Air pollution can cause both airplane and auto accidents because it cuts down visibility (能见度). There are other possible health dangers from air pollution that we don’t know much about. For example, scientists are trying to find out whether chemicals that reach us from the air may cause changes in our cells. These changes might cause babies to be horn with serious birth defects (缺陷，缺点). Scientists are trying to learn how all the many chemicals we are apt to take into our bodies from air, water, food, and even medicines act together to affect our health and the way our bodies work. That is another reason why it is so important to begin to control pollution now instead of waiting until we learn all the answers.

　　Air pollution costs us a lot of money. It corrodes (腐蚀)our buildings. It damages farm crops and forests. It has a destructive (毁灭性的) effect on our works of art. The cost of all this damage to our government is astronomical (极大的). It would be much more worth while, both for us and for the environment, to spend our tax dollars on air pollution control.

1．The direct cause of air pollution is ________.

[　　]

A．dark smoke from stacks or a burning dump

B．tiny bits solid or liquid matter

C．lots of invisible gases

D．chemicals in the air

2．Which of the following is NOT the bad effect of air pollution?

[　　]

A．Keeping us from seeing the sun.

B．Killing babies and older people.

C．Spreading diseases.

D．Causing car accidents.

3．The reason why air pollution can cause plane accidents is that ________.

[　　]

A．it irritates our eyes

B．it causes us to cough

C．it keeps us from seeing clearly

D．it increases the risks of lung diseases

4．Some babies are born with serious illness because of ________.

[　　]

A．black snow

B．respiratory diseases

C．chemicals in the air

D．damage to crops and forests

5．The purpose of the passage is to ________.

[　　]

A．explain what is air pollution

B．show how terrible air pollution is

C．discuss whether air pollution can cause changes in our cells

D．persuade people to spend mere money on air pollution control