并不是我们前面看到过的等号，或者双箭头。

It's not an equals sign like we've seen before, or a double arrow.

youdao

请点击“主题”字段旁的双箭头。

Tap the double arrows next to the subject field.

youdao

一端或两端带有双箭头的直线。

Line that can have a double arrowhead appear at either end, or both ends.

youdao

But since in drawing Lewis structures actually, in some cases you do, you can draw a dotted line that means a 1 and 1/2 bond, but most in most cases, we just draw out both resonance structures, and the way that we say it's a resonance structure is that we put it in the brackets and we put an arrow between it.

但是由于在画路易斯结构时,其实，在某些情况下是可以的，你可以画一条虚线来表示一又二分之一键，但是在多数情况下，我们就把两个结构都画出来，而我们说这是一个共振结构的表示的方法是,把它们放在括号里，并在中间放一个双箭头。

麻省理工公开课 - 化学原理课程节选