单项选择题
Heat energy is a source of power, but （） will cause damage to the engine.
A.excessive heat B.insufficient heat C.effective cooling D.high output
单项选择题 Head tank should be used to remove （） from cooling water.
单项选择题 He said that he had turned the main engine one complete revolution with the （）.
单项选择题 Generally the gudgeon pin is fully floating in both connecting rod small end and （）.
