catch sb off guard
使某人措手不及；出乎某人意料；趁某人不备
Sentences
Don't get caught off guard — always have a backup plan.
别被打得措手不及——时刻准备好备用方案。
常用于被动语态 be/get caught off guard，表示“猝不及防、毫无防备”。口语与书面语均常用。
Examples
- His sudden question caught me completely off guard.他突然提出的问题让我完全措手不及。
- The company was caught off guard by the sudden drop in sales.这家公司被销量的骤降搞得猝不及防。
Synonymstake sb by surprise, catch sb unawares, catch sb napping