完形填空。 when Chinese people find out that someone comes from London, they often say, 'London is a foggy city, isn't it?' British people who visit China often 1 say that London is not a foggy city at all!But if London is not foggy. 2 bo so many people in China think it is?In tact, London used to be a foggy city, 3 in isn't any more. In London peole of this it in pollution (污染) came from factories, but a lot of it came from coal (煤) because people used it in their houses 4 warm duing the winter.By the 1950s, Long-don's air pollution had became so 5 that the govemment (政府) decided to do something to clean up the air. A new rule was made. It said that 6 was not allowed to bum (燃烧) cosl in any British city. Just a few years 7 , the air became much cleaner. Now many Chinese cities meet the same kind of 8 with air pollution that London met forty or fitty years ago. However.this problem is more difficult for Chinese cities to 9 . First, more of the pollution comes from big fsctoies than from coal that pcople use in their houses. If these fac-lories are suddenly closed, lots of people 10 their jobs.Second, cleaner fuels(燃料)are quite expensive. However, the air in many cities is 11 slowly becoming cleaner,because the govem-ment and ordinary people are trying to make pollution 12 . As a result,the air in Beijing is get-ting cleaner and cleaner. (     )1. A. must (     )2. A. what (     )3. A. and (     )4. A. to keep (     )5. A. well (     )6. A. somebody (     )7. A. before (     )8. A. problem (     )9. A. find (     )10. A. lost (     )11. A. almost (     )12. A. liule B. have to B. when B. but B. keeping B. good B. anybody B. ago B. question B. answer B. lose B. already B. less C. should C. which C. SO C. kept C. badly C. nobody C. later C. accident C. solve C. would lose C. hardly C. much D. Will D. why D. or D. keep D. bad D. everybody D. after D. discussion D. save D. will lose D. nearly D. more