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.deviation C.firing order D.phase
单项选择题 Engage the flywheel with the （）.
单项选择题 Energy losses due to （） occur in every machine.
单项选择题 Emulsion oils and sodium nitrite are both approved additives, but （） cannot be used if any pipes are galvanized or if soldered joints exist.
