单项选择题 The connecting rod is fitted between the crosshead and the crankshaftI t transmits the firing force, and together with the crankshaft converts the （）motion to a （）motion.

单项选择题 The intake ports of a two-strike/cycle diesel engine are opened and closed by the action of the （）

单项选择题 Valves in the cylinder head of a diesel engine are opened by the direct action of the（）