It's not easy to follow her think because she's always go off at a tangent.
要跟上她的思路并非易事, 因为她老是突然扯到题外去。
The teacher was telling us about the poet's life, when he went off at a tangent and started talking about his war experiences.
老师在给我们讲述诗人生平故事的时候, 突然把话题一转, 讲开他自己的战争经历来了。