单项选择题
The cross-head shoes are white metal lined, grooves being cut horizontally on the face of the white metal to ensure （）.
A.an adequate supply of lube oil B.an adequate supply of fuel oil C.an adequate supply of turbine oil D.an adequate supply of cylinder oil
单项选择题 The cross-head shoes are white metal （）.
单项选择题 The crankshafts of medium speed engines are almost invariably solid （） from a single piece of steel.
单项选择题 The crankshaft receives and transmits the full working power of the engine and is subjected to fluctuating （）.
