How much sleep does a person need
(31) the physiological bases of the need for sleep remain
conjectural (猜想), rendering conclusive answers to this question impossible, much
evidence has been gathered on how much sleep people do in fact obtain. Perhaps
the most important conclusion to be (32) from this evidence
is (33) there is great variability among individuals in total
sleep time. For adults, (34) between six and nine hours of
sleep as a nightly average is not unusual, and 7.5 hours probably best expresses
the norm. Such norms, of course, forms inevitably vary with the criteria of
sleep employed. The most (35) and reliable figures on sleep
time, including those cited here, come from studies in sleep laboratories, where
EEG criteria are employed. (36) consistently has been associated with the varying A. is spent B. are spent C. spent D. spending [判断题]1078
A.正确 B.错误 [单选题]【单选题】影响悬停稳定性的因素不包括( )
A.起落架形式 B.风的影响 C.地面效应的影响 [单项选择]下列哪项检查对急性胰腺炎的诊断价值最大()
A. X线 B. 腹部B超 C. 核素扫描检查 D. 腹部CT E. 胃镜 [单选题]高压试验现场装设的遮拦应( )的标示牌。
A.向内悬挂“止步,高压危险!” B.向外悬挂“止步,高压危险!” C.向外悬挂“在此工作!” [单项选择]胆管细胞囊腺癌的CT表现,不包括()
A. 实质部分为低密度 B. 囊壁厚薄不均 C. 可见囊壁结节 D. 囊内液体密度 E. 病变显著强化 [单选题]下列关于电子束焊真空室的说法错误的是( )
A. 真空室的尺寸及形状应根据焊机的用途和被加工的零件来确定 B. 真空室一般采用低碳钢和不锈钢制成,碳钢制成的工作室内表面应镀镍 C. 电子束焊机的使用者可自行改装真空室 我来回答: 提交
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