Flex and bend.

灵活、弯曲。

youdao

Notice how your ankles flex, how your calf muscles contract and how your knees bend.

留意你的踝关节如何曲伸，小腿肚上的肌肉如何收紧和膝关节如何弯曲。

youdao

Although effort is required to bend a joint or flex a muscle, the body is able to recycle much of the energy expended through spring-like tendons and elegantly arranged muscles.

尽管需要花力气去弯曲关节或拉伸肌肉，但人体可以利用弹簧般的肌腱和分布优雅的肌肉来回收相当部分的能量。

youdao

As we've said many times before, it feels as if the keys have been molded especially for our fingertips and the deck itself doesn't have any flex or noticeable bend.

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