《煤矿安全规程》规定,滚筒式采煤机必须安装内、外喷雾装置。截煤时必须喷雾降尘,内喷雾压力不得小于()。
A.2.0MPa
B.1.5MPa
C.1.8MPa
参考答案:A
森林脑炎病毒的传播媒介是()
A.蚊
B.蜱
C.蚤
D.虱
E.螨
None of them have regular and ________source of income and they are forced to live below poverty line.[ ]
A. safe
B. legal
C. secure
D. diverse