粒子符号上加一横，用来表示反粒子。

A horizontal bar over a particle symbol is used to designate the antiparticle.

youdao

当时我心一横，“反正现在再改也来不及了！”

Well, I thought, "It is too late to change."

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接着，又对人的现实存在进行了一纵一横两方面的分析。

Then the article analyzes the realistic existence of mankind in the longitudinal and horizontal aspects.

youdao

So I can make a quantity that I'll call V bar, which is the molar volume, the volume of one mole of a component in my system, and that becomes an intensive quantity.

所以我可以定义，一个叫做一横的量，这是摩尔体积系统中,一摩尔某种组分的体积，它就变成了。

麻省理工公开课 - 热力学与动力学课程节选

I'm going to put a little bar right here.

这一横表示。

麻省理工公开课 - 热力学与动力学课程节选

Now I'm going to add a little thing here.

注意我们需要在这上面加上一横。

麻省理工公开课 - 热力学与动力学课程节选