4周搞定2000+托福核心词
vacuum
常考释义
The original patent outlined a three-stage process, in which phenol and formaldehyde (from wood or coal) were initially combined under vacuum inside a large egg-shaped kettle.
最初的那份专利描述了一个分为三步的工艺过程。首先，苯酚和甲醛(来自于木头或木炭)在一个巨大的椭圆体真空罐内发生化合作用。
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