问题描述：
Somwe people go to bed at night and get up late in the morning.This is not good for them.
We must _____ at night when it is dark.
The dark helps us to sleep well.When day breaks,we must get up.It is t___ for exercises.Exercise means doing things with the body.
We must _____ at night when it is dark.
The dark helps us to sleep well.When day breaks,we must get up.It is t___ for exercises.Exercise means doing things with the body.
问题解答：
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