井下采掘工作面的进风流中,二氧化碳的浓度不高于( )。
A.2.0%
B.15%
C.1.0%
D.0.5%
参考答案:D
There is ______ with your watch. It doesn't work. [ ]
A. something wrong
B. anything wrong
C. wrong something
D. everything wrong
提升机制动装置的传动机构是控制、调节或解除制动的机构,可分为()、()、空气压力等。