Spring tendons enhance the foot’s efficiency: some of the energy spent to drop one’s weight down when taking a step is actually stored and then returned to the leg as it rebounds.

人们走路每迈出一步，重量落下时所输出的一部分能量，事实上被脚弓存储起来，然后被脚弓弹起，这部分能量就又返回到腿部。

youdao

So a few weeks after my birthday, in the spring of 2006, I walked into the office of a weight-loss doctor.

于是在2006年春天，在我过完生日的几个礼拜后，我走进了减肥医生的办公室。

youdao

But, just like I didn't lose this much weight and body mass in a week or a month, my doctors expect it will take until late this spring to regain it.

不过，我不是在一周或者一个月之内瘦了这么多的，相应地，我的医生预计我要到今年春季后期才能恢复过来。

youdao

You are pushing down with the weight mg, and the floor has got to be pushing up with the mg, because the spring is not going anywhere.

你向下的作用力是重力 mg,然后地面向上的支持力也是 mg,因为弹簧现在根本没动

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Like a spring with a heavier weight at one end, the vibration frequency is lowered, and flies appear to notice.

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The use of a rechargeable battery, which can be charged up with energy from the spring several times, and then occasionally topped up during use, dramatically reduces its size and weight.

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