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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】目前世界上已证明达菲是能治疗禽流感的唯一良方．莽草酸（C7H10O5）是生产达菲的原料之一，下列关于莽草酸的说法错误的是（ ）
A.
相对分子质量为174
B.
碳元素质量分数大于氧元素质量分数
C.
莽草酸中有7个碳原子、10个氢原子、5个氧原子
D.
莽草酸中C、H、O元素的质量比为84：10：80