单项选择题
No sooner （） than they started to repair the sludge pump.
A.the second engineer had got into the engine room B.the second engineer got into the engine room C.has the second engineer got into the engine room D.did the second engineer get into the engine room
单项选择题 （）the moveable plate and floating ring inside the pump is very difficult.
单项选择题 The four-stroke cycle begins with the piston （）.
单项选择题 Pump up the starting air reservoirs to their maximum pressure and （）the air reservoirs and air system.
