名詞 tangent:

1. a straight line or plane that touches a curve or curved surface at a point but does not intersect it at that point
2. ratio of the opposite to the adjacent side of a right-angled triangle
   同義詞：tan

1. 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，因為她老是突然扯到題外去。
2. The teacher was telling us about the poet's life, when he went off at a tangent and started talking about his war experiences.
   老師在給我們講述詩人生平故事的時候，突然把話題一轉，講開他自己的戰(zhàn)爭經歷來了。