根据短文内容，从方框中选择合适的单词填空。 energy, invent, dr
题型：填空题
问题：
| 根据短文内容，从方框中选择合适的单词填空。 | |
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| The bicycle is one of the simplest yet most useful inventions in the world. What is the most surprising is that it was not (1)__________ earlier, although the great inventor Leonardo da Vinci had (2) __________ pictures for bicycles and flying machines and some other things. Those things were not produced (3) __________ long after he died. A person riding a bicycle uses very little (4) __________ to make the bicycle move, and there is no pollution at all when you are riding. Even so, in most develope  d (5) __________, most people don't go to work by bicycle. It is not (6) __________ the bicycles are expensive or people feel (7) __________ if they ride to work. It's because the number of cars on the roads becomes larger. It certainly becomes more (8) __________ to ride a bicycle. As a result, more people put their bicycles away and go to work (9) __________ their cars. And in this way, the situation is made more serious. Perhaps the best way to make riding safer and more popular is to (10) _____ _____ paths only for bicycles. |