The pump has a constant stroke and the amount of fuel delivered is regulated by rotating _

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The pump has a constant stroke and the amount of fuel delivered is regulated by rotating _____ which has a specially arranged helical groove cut into it.

A.the pump cylinder

B.the pump cam

C.the pump plunger

D.the pump miler

请帮忙给出正确答案和分析,谢谢!

热搜:a是b的充分条件,b是a的必要条件吗