为保证变速器很好地工作，设计变速器时应当满足哪些主要要求？
参考答案：
（1）保证汽车有必要的动力性和经济性。
（2）设置空档，用来切断动力。
（3）设置倒档。
（4）设置动力输出装置。
（5）换档迅速、省力、方便。
（6）工作可靠，无跳档、乱档、换档冲击现象。
（7）传动效率要高。
（8）工作噪声低。
（9）尺寸小，质量小，成本低，维修方便。
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| Hearing is very important to all of us. We can 1 beautiful music, nice songs of birds, the laughter of people or other different kinds of 2 in the world with our ears. 3 we must try to protect our ears. The following will tell you 4 protect ears. Listening to 5 music a lot can be bad for ears, 6 when headphones (耳机) are used. So try not to wear headphones or 7 the volume (音量) when you're wearing headphones. You should give your ears a rest if you like wearing headphones. Before swimming, remember 8 earplugs (耳塞) into your ears or wear a swim hat to stop water 9 into your ears. If you are going to a concert, wear earplugs to protect your ears 10 the terrible music! 11 , special earplugs can be made for you if you go to concerts a lot or if you are a musician yourself. See a doctor if your ears 12 . 13 some medicine if the doctor asks you to do so. 14 the advice above now and you won't be saying "what?" when you are getting 15 . | ||||
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