The main idea of the passage is to______.
A．illustrate what enough sleep is through tests
B．explain that cognitive performance remains intact with less sleep
C．clarify that countermeasures can help to release sleepiness
D．demonstrate ways to make up for sleep deprivation

A.
A．illustrate
B.explain
C.clarify
D.demonstrate

【参考答案】

A
主旨题。这篇文章主要介绍丁格斯所进行的实验。为了知道充足的睡眠到底是多长时间，科学家们进行了多种有关睡眠的实......

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