By this time, the heart's electrical signal has passed from the atria into the ventricles, so while the atria relax, the ventricles contract.

这个时候，心脏发出的电信号从心房传到心室，所以当心房放松时，心室就收缩。

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It takes diligence to identify your pelvic floor muscles and learn how to contract and relax them. Here are some Pointers.

找到盆底肌的位置，学会如何收缩和放松肌肉，不断地练习让自己熟练掌握这一技巧。

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Researchers said: 'Once the ink on the marriage contract dries up, they relax the control they had on their weight and appearance.'

研究者说，“结婚证上的签字刚刚晾干，夫妻俩就不再强调要保持体重和外表了。”

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It has a very well-developed muscular tissue and its function is to contract and relax, contract and relax.

该肌肉组织非常发达,用来使心脏收缩,放松,收缩,放松

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"We get it to contract and relax, like biological muscle, " said Dr Ma.

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