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【单选题】第二篇 Sleep We all know that the normal human daily cycle of activity is of some 7 - 8 hours’ sleep alternating with some 16 - 17 hours’ wakefulness and that, broadly speaking, the sleep n...
A.
people hate the inconvenience of working on night shifts.
B.
your life is disturbed by changing from day to night routines and back.
C.
not all industries work at the same hours.
D.
it is difficult to find a corps of good night workers.
【单选题】第八章~第十章
A.
肾上腺素减慢心率是由于（ ）
B.
降低外周阻力
C.
直接抑制心血管中枢的调节
D.
血压升高引起的继发效应
E.
直接负直接负性频率作用
F.
抑制心肌传导
【单选题】最概然速率Vp的物理意义是( )。
A.
Vp是速率分布中最大速率
B.
Vp是大多数分子的速率
C.
在一定的温度下，速率与Vp相近的气体分子所占的百分率最大
D.
Vp是所有分子速率的平均值