touch on

The article touched on the main problem.

文章提到题。

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

想简单地谈这个题的另方面。

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

他关于地质学的报告中, 也涉及气候题。

He touched me on the arm.

他碰了的手臂。

Such actions touch on betrayal.

这种行为近乎背叛。