单项选择题
It is very important that each cylinder should be （） scavenged before the charged air is compressed.
A.well B.good C.excellent D.respectively
单项选择题 It is necessary to remove （） from the cooling water spaces to improve heat transfer.
单项选择题 It is necessary to remove （） from the cooling spaces.
单项选择题 It is necessary to （） cool the various components of the machinery so that the engine can work properly.
