长难句：For example, it has long been known that total sleep deprivation is 100 percent fatal to rats, yet, upon examination of the dead bodies, the animals look completely normal.
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n结构剖析：本句由表示转折关系的连词 yet 分为两个部分：第一部分的主干是 it has long been known that...，其中it 是形式主语，that 引导的主语从句作真正的主语；第二部分的主干是 the animals look completely normal，前面的 upon examination of the dead bodies作状语。
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n核心词汇：deprivation 剥夺 fatal 致命的