单项选择题
The cleaned heated oil, after passing through the centrifuges, is to be pumped to a （）.
A.settling tank B.service tank C.ballast tank D.drain tank
单项选择题 The cast iron guide-ways for （） are attached to the top section and seal off the crankcase.
单项选择题 The cast iron（）for the cross-head are attached to the top section and seal off the crankcase.
单项选择题 The carbon deposits on the piston crown and in the ring grooves （）.
