A.it is much easier to become a professional today than it was in the past.
B.there is more social intercourse between professionals and others.
C.popular science has told their secrets to the world.
D.anyone can now understand anything in a profession.
第1题
A.0.5%
B.1.0%
C.1.5%
D.2.0%
第6题
设在回风流中的井下机电设备硐室,此回风流中的瓦斯浓度不得超过0.5%,并必须安装()。
A 便携瓦斯检查仪;
B 一氧化碳传感器;
C 甲烷断电仪
第8题
采煤工作面回风流中瓦斯浓度大于(),甲烷传感器将发出声光报警并发出断电命令。
A.0.5%
B.1.0%
C.1.5%
D.2.0%
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