点击下方单词,选择对的这个单词
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1. 活塞A piston is a cylinder or metal disc that is part of an engine. Pistons slide up and down inside tubes and cause various parts of the engine to move.
1. mechanical device that has a plunging or thrusting motion
Synonym: plunger
多通过句子记忆单词，而不是单独死记硬背。
