完形填空 The bicycle is one of the simplest yet most useful inventions in the world. What is most surprising is that it was not 1 earlier, although the great inventor Leonardo Da Vinci had drawn pictures for bicycles and also for flying machines and some other things. Those things were not produced 2 long after he died. A person riding a bicycle uses 3 energy to make the bicycle move, and there is no pollution at all when you are riding. Even so, in developed 4 , most people don't travel to work by bicycle. It is not because the bicycles are expensive or people feel 5 if they ride to work. It's because 6 cars on the roads becomes larger. It certainly becomes 7 to ride a bicycle. As a result, more people put their bicycles away and go to work 8 their cars, and in this way, the situation is made more serious. 9 the best way to make riding safer and more popular is to create paths(开设通道) only for bicycles, and to make 10 so difficult and expensive for drivers to take their cars into the city that they will go back to use their bicycles. (     )1. A. invent (     )2. A. before (     )3. A. much (     )4. A. world (     )5. A. tired (     )6. A. the number of (     )7. A. safer (     )8. A. by (     )9. A. Hardly (     )10.A. it B. inventing B. until B. quite a lot of B. countries B. glad B. a number of B. more dangerous B. in B. May be B. them C. invented C. since C. very little C. land C. sorry C. this kind of C. much dangerous C. use C. Perhaps C. that