还有那些按钮也很难对付，但我还是搞明白了：“放入”键是个直角三角形，“停止”键是两条竖线。

It's rather hard to deal with buttons, but I managed to do it: "Insert" is a right triangle, "Stop" - two vertical lines.

youdao

这里三角形是因为,我们有3个原子核中心原子成键，如果你画它，它就是金字塔形的。

So it's trigonal because we have these three atoms that are bound to the central atom here, and if you picture it, it's actually shaped like a pyramid.

youdao

按下Cmd和Opt键的同时击这个三角形符号，可以折叠或展开所有层级的群组文件夹。

Hold down Cmd + Opt + click on the triangle icon will collapse or expand all level layer groups.

youdao

So it's trigonal because we have these three atoms that are bound to the central atom here, and if you picture it, it's actually shaped like a pyramid.

这里三角形是因为,我们有3个原子核中心原子成键，如果你画它，它就是金字塔形的。

麻省理工公开课 - 化学原理课程节选