夏天C25混凝土从搅拌机中卸出后到浇筑完毕的延续时间不大于（ ）
A. 60
B. 90
C. 120
D. 150
查看答案
下面说法正确的是（ ）
A. 运输中的全部时间不应超过混凝土的终凝时间
B. 运输中应保持匀质性，不应产生分层离析现象
C. 运至浇筑地点应具有规定的坍落度
D. 混凝土的运输道路要求平坦
E. 最少的运转次数、最短的时间从搅拌地点运至浇筑地点
How to properly ask passengers to turn off mobile phone for take-off?
A. Could you please switch off your cell phone?
B. Would you please turn off your mobile phone?
C. Smoking is not allowed.
D. Remote-controlled equipment is prohibited.
What devices are not permitted to use for take-off and landing?
A. mobile phone
B. radios
C. laptop computer
D. remote-controlled equipment
飞机起飞时可以使用充电宝给手机充电。
A. 对
B. 错
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