题目内容:
Thepurposeofnon-REMsleepisevenmoremysterious.Thenewexperiments,suchasthose_____forthefirsttimeatarecentmeetingorthesocietyforSleepResearchinMinneapolis,suggestfascinatingexplanationsforthepurposeofnon-REMsleep.[A]maintained
[B]described
[C]settled
[D]afforded
参考答案:
答案解析: