单项选择题 It should be evident that the amount of fuel injected into the cylinder is dependent on the position of the helix relative to the （）.

单项选择题 As the plunger moves upwards in the barrel, injection will commence once the plunger has （） the spill ports and the pressure builds up.

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