放两个重物在活塞上。

We have two weights on it.

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考完试候，我们将放两个星期的假。

After the exam, we'll have two weeks' holiday.

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这场电影大约要放两个小时。

This film will last about two hours.

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So, step five tells us to add 2 electrons between each atom, so we add two there.

那么，第五步告诉我们在两个原子之间放上两个电子，因此我们在这放上两个。

麻省理工公开课 - 化学原理课程节选

And then I could put a couple of plates and I could raster the beam so that when I am looking here,the beam goes back and forth about 80 times a second.

然后我放了两个感光片,我可以检测到光束所以,当我观察时,电子束以每秒80次的速度来来回回了。

麻省理工公开课 - 固态化学导论课程节选

So, the first thing we do is put two electrons between h and c, and then two electrons between c and n.

那么，我们先在氢和碳之间放两个电子，然后在碳和氮之间再放两个电子。

麻省理工公开课 - 化学原理课程节选