In ancient China, hand fans were almost the only ones to help people keep cool.

在古代中国，手扇几乎是唯一的帮助人们保持凉爽的工具。

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In order to describe human beings, he should keep the palm of his hand at a right angle to the floor.

为了描述人类，他应该保持手掌与地面成直角。

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She retired last year but still teaches the odd class to keep her hand in.

她去年退休了，但偶尔还上课，以免技巧生疏。

《牛津词典》

On average,students using swear words were able to keep their hand in the water for about two minutes.

VOA: special.2009.08.18

On the other hand, temperature, volume and pressure are variables that are much easier in the lab to keep constant.

另一方面，温度，体积和压强,在实验室中比较容易保持恒定。

麻省理工公开课 - 热力学与动力学课程节选

With Leinster playing against a stiff breeze in the first half the hosts were always going to keep the ball in hand where possible.

BBC: Leinster 22-9 Leicester

Always keep your belongings in hand, and try not to wear flashy clothing or jewellery that might make you stand out as a target.

BBC: Central America��s shift in safety

However, the generals have little choice but to keep a hand in guiding the country through its crisis, since they stand to be blamed if it all goes wrong.

ECONOMIST: The junta's stumbling first steps