touch on

In his lecture on geology, he touched on the subject of climate.

他在关于地质学的报告中, 也涉及气候题。

I want to touch briefly on another aspect of the problem.

我想简单地谈题的另方面。

The article touched on the main problem.

文章提到主要题。

He touched me on the arm.

他碰了我的手臂。

Such actions touch on betrayal.

种行为近乎背叛。