单项选择题
A.one half crankshaft speed in a two-stroke cycle diesel engine
B.crankshaft speed in a two-stroke cycle diesel engine
C.two times crankshaft speed in a two-stroke cycle diesel engine
D.one-fourth times crankshaft speed in a four-stroke cycle diesel engine
单项选择题 The abbreviation ‘M/E’ is used to represent the（）
单项选择题 Where tanks are arranged for either oil or ballast （） must be fitted in the pipe so that only the ballast main or the oil transfer main connected to the tank.
单项选择题 The switchboards are those in which all the live parts are installed behind the panels and only the operating handles and instruments are on the front（）