机械台班定额可分时间定额和产量定额，且它们互为倒数关系。
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红外碳硫仪所使用的载气是（）。
A. 氧气
B. 氩气
C. 氦气
D. 氮气
68～70℃糖化对β-淀粉酶有利，62．5℃糖化对α-淀粉酶有利。
A. 正确
B. 错误
As soon as you hear the fire and emergency signal, you should ensure that the （）.
A. ring buoys are thrown overboard
B. engines are stopped
C. fire pumps are started
D. life preservers have been issued to everyone
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