But why should they sleep deeply at all?
但是动物为什么要进入深度睡眠呢？
This will help them sleep deeply and peacefully.
这将帮助他们睡得很沉，很安详。
The heaviness of his heart caused him to sleep deeply.
他心情忧郁，就沉沉入睡了。
The darker the room, the easier it is to sleep deeply.
房间越漆黑，深度睡眠就越容易。
They sleep very deeply, and need little or no food.
他们睡得很沉，几乎不需要进食。
Rest deeply. Get enough sleep.
好好休息。保持充足的睡眠。
I cannot believe I could sleep that deeply.
我不相信自己能睡得那么沉。
I cannot believe I could sleep that deeply.
我不相信自己能睡得那么沉。
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