单项选择题
A.excessive water in the bilges
B.a clogged suction strainer
C.oil in the bilges
D.All of the above
单项选择题 The shaft and spare parts（） should be well greased in order to avoid corrosion.
单项选择题 Water level controllers of the boiler must be kept operable to protect external steam-using plant from water “（）” danger.
单项选择题 The （） of the gravity disc is too big It causes oil to flow through the water outletWe changed the disc and no oil is found in the water outlet.