问题
问答题 简答题
简述琴弦振动所需的条件。
答案
参考答案：
弦的振动方式属于机械波的一种，弦就是传播波的媒质。琴弦被弦槌敲击而发生振动需要张力，而得以构成张力的最基本条件是弦两端必须有两个支点。
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简述琴弦振动所需的条件。
参考答案：
弦的振动方式属于机械波的一种，弦就是传播波的媒质。琴弦被弦槌敲击而发生振动需要张力，而得以构成张力的最基本条件是弦两端必须有两个支点。
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| Boys and girls love to watch TV. Some children 1 six hours a day in the school and sit four to six hours a day 2 the TV sets. Some children even (甚至) watch TV for eight or 3 hours at weekends. Sometimes TV programs (节目) are 4 and a child can know a lot of things from them. It’s very 5 to watch TV. 6 sometimes TV can also teach children some 7 things. It’s not good for children to watch 8 TV and it’s bad for their 9 , too. So, boys and girls, don’t watch too much TV. It’s also very interesting to read 10 or to visit friends. | ||||
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