It also tells you that if you compress the spring, compress it means x is now-- x is measured from this position, where the spring is neither compressed nor expanded.

它还能告诉你,如果压缩弹簧,压缩就意味着现在 x...,x 是从这个位置开始算的,在这个位置弹簧既没有压缩也没有伸长

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