The normal human daily cycle of activity is of some 7-8 hours’ sleep alternation with some 16-17 hours’ wakefulness and that the sleep normally coincides (1)_______the hours of darkness. Our present concern is with how easily and to what extent this (2)_______can be modified. The question is no mere academic one. The ease with which people can change from working in the day to working at night is a (3)______of growing importance in industry where automation (4)_______round-the-clock working of machines. It normally (5)______from five days to one week for a person to adapt to a (6)_______routine of sleep and wakefulness, sleeping during the day and working at night. (7)_______, it is often the case in industry that shifts are changed every week. This means that no sooner has he got used to one routine (8)_______ he has to change to another, (9)_______much of his time is spent neither working nor sleeping very (10)_______. One answer would seem to be (11)_______periods
A. as
B. when
C. then
D. than
| Scientific research has revealed that
throughout the animal world, communication is just as important as it is to
human beings. Countless animals lack the{{U}}(67) {{/U}}for human speech, yet
they employ entirely different methods in order to communicate{{U}}
(68) {{/U}}each other. Some of the most dramatic examples of this are
provided by birds. There are roughly 10 000{{U}} (69) {{/U}}of birds in
the world, each of which has its own miraculous features. {{U}} (70)
{{/U}}you may live, you can see a great number of these feathered creatures
and can {{U}} (71) {{/U}}different and extraordinary properties. In
addition to their flawless flight mechanisms, expertise{{U}} (72)
{{/U}}the routes and timing of migrations, and ability to build nests, their
methods to communicate is{{U}} (73) {{/U}}wonder. At critical
times in birds’ lives, A. groups B. species C. classes D. regions [单项选择]下列必须重载为成员函数的运算符是 ______。
A. +和-＞ B. =、[ ]和() C. ++、=和[] D. +=、[]和= [单项选择]卫生工作者大气污染对健康影响的调查监测目的不包括（）
A. 查明大气污染来源 B. 查明大气污染种类、浓度 C. 查明大气污染范围和污染规律 D. 查明大气污染对人体健康造成的危害 E. 根据污染状况给予罚款 [多选题]以下那几项属于船外机库存放置：( )。
A.发动机内部应使用润滑油保养 B.船外机外部应经常擦拭保持清洁 C.使用后应在黄油加注处加黄油进行润滑 D.应使用外壳保护套进行保护 [单项选择]铸造钴铬合金中，钴的主要作用是（）
A. 增加合金强度和硬度 B. 降低合金熔点 C. 提高合金可塑性 D. 改善合金流动性和铸造性能 E. 降低合金弹性模量 [判断题]小粒度生球落下强度比同条件下大粒度的要高。
[判断题]万吨列车始发站挂车时，后小列执行两停一挂。( )
A.正确 B.错误 [单选题]影响酶促反应速度的因素不包括
A.底物浓度 B.酶的浓度 C.反应环境的pH D.酶原的浓度 E.反应温度 [判断题]从业人员有权对本单位安全生产工作中存在的问题提出批评、检举、控告;有权拒绝违章指挥和强令冒险作业。()
A.正确 B.错误 我来回答: 提交
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