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。
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。
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。”
It sends carefully timed signals that make the right and left ventricle contract and relax in unison.
双腔起搏器能够定时发送信号，来使左右心室一同收缩、舒张。
The limbs no longer have weight, so muscles are no longer required to contract and relax in the usual way to maintain posture and bring about movement.
肢体不再有重量，所以肌肉再也不需要收缩、放松来保持某种姿势或促成运动。
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。”
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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