Some （） lying in the starting air lines will give rise to corrosion and can cause water hammer.

A.drained off
B.collected
C.sent to the crankcases
D.separated with oil

A.rotary compressors
B.reciprocating compressors
C.centrifugal compressors
D.screw compressors

A.starting diesel engines
B.pneumatic control systems
C.pneumatic tools
D.supercharging air