A cellist is always shortening and lengthening the strings.

大提琴演奏家总是在压缩或拉长弦

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because we're prolonging basically a train wreck,

因为我们把烂摊子拉长了，

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It is pulled by a certain amount x, and is released.

将弹簧拉长一段距离 x,并释放

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