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　　The earth is our home. We must take care of it. Life today is easier than it was (1)_______ years ago, but it has brought some new problems. One of the biggest problems is pollution. We can see it, smell it, drink it and even hear it.
　　Man has polluted the (2)______. The more people, the more pollution. Many years ago, the problem was not so serious because there were not so (3)____ people. When the land was used up or the river was not clean in a place, man went to (4)______ place. Now man is slowly polluting the whole world.
　　(5)_____ pollution is still the most serious, it's bad for (6)_____ things in the world.
　　Many countries don't let people burn (7)_____ for air in the houses and factories in the city. Pollution by SO2 is now the most dangerous kind of air pollution. It's caused by heavy traffic. People say it's (8)______ to ride bikes. When you are riding, there is no pollution. But even in developed countries, most people don't go to work by bike. It's not because bikes are expensive or people are tired if they ride to work. It's because the number of cars on the roads becomes larger. So more people (9)______ their bikes and go to work by car, then things are getting worse and worse. We should have special roads only for bikes and make it (10)______ difficult and expensive for drivers to take their cars into the city that they will go back to using their bikes.
　　( )1. A. hundred B. hundreds of C. hundred of D. hundreds
　　( )2. A. moon B. star C. earth D. sun
　　( )3. A. lot B. little C. many D. much
　　( )4. A. others B. the others C. the other D. another
　　( )5. A. Air B. Food C. Water D. Noise
　　( )6. A. life B. live C. living D. lives
　　( )7. A. something bad B. bad something
　　C. something good D. good something
　　( )8. A. least B. best C. most D. worst
　　( )9. A. put on B. look at C. put away D. look up
　　( )10.A. quite B. such C. very D. so
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