Adequate attention must be given to the water cooling system of the air compressors, for （） can cause condensation on the cylinder walls.

A.the discharge temperature low
B.the discharge temperature high
C.the discharge pressure rise
D.the inter-stage pressure low

A.the lubrication
B.the cooling
C.the moisture separation
D.the valves

A.without first cooling it
B.without first heating it
C.without first unloading it
D.without first loading it