演讲者在谈论气候变化时，突然偏离主题讲起了自己的童年。

The speaker started to digress from climate change and talked about his childhood instead.

### 解释 digress 是动词，由前缀 di-（表示"离开"）和词根 gress（来自拉丁语 gradi，意为"行走"）组成，字面意思是"走开、偏离"。digress 指在讲话或写作时"偏离主题、跑题"。