单项选择题
Engine （） refers to the relative time of position of crank, at which each operation during the cycle is commenced and is completed.
A.timing B.power C.firing order D.dead center
单项选择题 Engine （） refers to the relative time of position of crank, at which each operation during the cycle is commenced and is completed.
单项选择题 Engage the flywheel with the （）.
单项选择题 Energy losses due to （） occur in every machine.
