London used to be "foggy" for the same reason that cities like Beijing' or Chongqing are "foggy~ today. The "fog was in fact smog, a mixture of smoke and fog.  In other words, it was made by air pollution  In London, some of this pollution came from factories, but much of it came from the coal that people burnt in their houses to keep warm during the winter. By the 1950s, London's smog problem had become so bad that the-government decided to do something to clean the air.  A new law was made and nobody could bum coal in any British city. Within a few years, the air became much cleaner. There were no more “pea-soupers”.             .
Many Chinese cities now face the same sort of' problem with air pollution that . London faced 40 0r 50 years ago.  However, this problem is more difficult for Chinese cities to solve   One reason is that more of the pollution comes from the factories, rather than from coal burnt in people's houses  If these factories were closed, this would harm the economy(经济） and lots of people would lose their jobs. Another reason is that changing from coal to cleaner fuel (燃料), like gas, is quite expensive.
However, the air in many Chinese cities is becoming cleaner and cleaner, as the government and people pay more and more attention to cutting down pollution . As a result,there are fewer "pea-soupers" in Beijing than there used to be.
根据材料内容选择最佳答案。
What was the main reason for air pollution in London?

A．There was too much smoke in the sky.

B．People burnt too much coal in the houses.

C．There were too many factories in the city.

D．The city was too big for the cleaners to clean.

How did the air in London become much cleaner?

A．Many factories in the city were closed

B．There was not so much fog in the winter later.

C．People paid more attention to cleaning their city.

D．A law was made to keep people from burning coal in their houses.

What does the 'underlined word "pea-soupers" refer to?

A．烟尘

B．吸烟

C．毒气

D．煤气

In China, air pollution is more difficult to solve  Which of the following is not the reason?.

A．Most pollution comes from the factories

B．Chinese government pays little attention to it.

C．Changing from 'coal to cleaner fuel is quite expensive

D．If factories were closed, this would harm the economy and lots of people would .lose their jobs.

What's the text mainly about? .

A．Air pollution in Beijing and Chongqing.

B．Air pollution in London

C．Air pollution: different cities, different ways

D．Coal burning.