John drives into the city. The motorway is full of trucks and cars. It is 8 o'clock and people are going to work in the factories and offices. The traffic stops. Then, it moves forward. Then it stops again. John listens to the radio in the cab of his truck. He can be patient, but today is different. He is in a hurry.
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And then when it stops again, I'll stop the time, and then we have half a period.
当它再一次停下，我停止计时，那么我们将得到半周期。
So if you rotate it three times and then let it go, it goes first three times back, then it's at equilibrium, and then it winds three times up again before it stops.
所以如果你旋转它3次,放开它，它会转3次回来，然后会达到平衡,在停止之前,会绕三次。
The cart stops. Then it starts again. "Now I can see just fine," says the goose.
马车停了。然后又出发了。“我现在都能看到了，”鹅说。
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