单项选择题
Measure （） by means of lead wire.
A.the clearance of the main bearing B.the play of the miler bearing C.the gap of the main bearing D.the tolerance of the main bearing
单项选择题 Marine four-stroke diesel engines are mainly （）.
单项选择题 Main bearings are required to support the crankshaft at each （）.
单项选择题 Lubricating oil for an engine is stored at the bottom of the （）, known as the sump or in a drain tank located beneath the engine.
