A.the lubricating pumps are stopped and the access doors are opened
B.the lubricating pumps are running and the access doors are opened
C.the engine is running and the access doors are closed
D.the engine is stopped and the access doors are closed

A.should be kept at a proper level by a cooler
B.should be raised to about 80℃ by a heater
C.should be raised gradually
D.should be lowered to about 60℃