单项选择题 It is important to note that the injection only takes place when the plunger is moving up the cam （）.

单项选择题 The high-pressure fuel opens the fuel valve and is sprayed into the cylinder in tiny droplets known as （）.

单项选择题 Because the timing of injection is crucial, （） mounted on the camshaft, which is driven by the crankshaft are used to operate the fuel pumps, one of which is provided for each cylinder.