循环水泵出水管上均应装设( )。
A.疏水阀
B.截止阀
C.止回阀
D.隔膜阀
参考答案:C
The table still _______where I ______them a few days before .
A.lay; lay
B.laid; had laid
C.lay ; had laid
D.were lying ; had laid
通过隧道时,不得超车。