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。

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And then he goes back to hell and then back up to heaven -goes back and forth between these two rhythmically very different concepts.

然后它回到了地狱,接着又升到了天堂,在这两种节奏非常不同的概念之间,来回往复

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So the bar just goes back and forth.

这个木杆可以来回移动

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