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, 也涉及气候问。

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

简单地谈一下个问的另一。

The article touched on the main problem.

章提到主要问。

He touched me on the arm.

他碰了一下的手臂。

Such actions touch on betrayal.

种行为近乎背叛。