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1.replace with 用…代替
例句：We've replaced the old machine with a computer.
我们用电脑取代了那台旧机器。
2.valve stem 阀杆
例句：The connecting rod may drive a valve stem directly.
连杆可以直接带动阀杆。
3.from to
例句：He swings from wild optimism to total despair.
他由极其乐观一变而为完全绝望。
4.begin doing 开始做某事
例句：How old were you when you first began playing the piano?
你几岁时开始弹钢琴？
