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.
A.sea cheat B.air receiver C.crankcase D.water box
单项选择题 Low compression results from （）.
单项选择题 Low compression of diesel engine may result from （）
单项选择题 Leaky exhaust valve will result in which of the following?（） (1) high exhaust temperature; (2) low compression pressure; (3) low firing pressure.
