每组压风自救装置应当可供5~8人使用,平均每人空气供给量不得少于()m3/min。
A.0.1
B.0.2
C.0.3
D.0.4
参考答案:A
Some children ______ pictures when the teacher came into the classroom.
A.draw
B.are drawing
C.were drawing
D.will draw
钻井液中固相含量越()越好。