The answer: wells that drill vertically down to the shale bed, then make a gradual 90-degree horizontal turn through the shale deposit.

目前，科学家提出了解决方案——先垂直钻探至页岩床位置，然后以90度水平地钻探页岩沉积层。

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NREM sleep is when you tend to toss and turn in bed. Your brain quiets down, which means that you aren't dreaming.

NREM睡眠状态是指身体在床上翻来覆去，但大脑趋于平静，意味着没有在做梦。

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After her children go to bed, the mother turn the upside-down house back to normal.

孩子们睡觉后，母亲把混乱的屋子重新整理好。

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