单项选择题
The oil sludge is burnt in the （）on board I’ll show you the ashes.
A.boiler B.main engine C.auxiliary engine D.incinerator
单项选择题 Before dismantling the pipe, would you （）the oil retained in the hose with （）?
单项选择题 The young motorman as well as the others （）to operate the oil separator.
单项选择题 No sooner （） than they started to repair the sludge pump.
