单项选择题
The bearing shell generally has （） for location and oil grooves round the center of its axial length.
A.tips B.tags C.lips D.keys
单项选择题 The auxiliary engine and a cgenerator can be connected with （）.
单项选择题 The amount of lubricating oil in the drain tank should be checked by （）.
单项选择题 The abbreviation TDC means （）.
