a red flag

含义

a sign that something may be wrong or dangerous

可能出问题或有危险的迹象.

例句

1. 1A landlord who won't show you the flat before you pay is a red flag.
2. 2The missing reviews were a red flag, so we booked a different hotel.
3. 3When the seller asked me to pay in cash before I'd seen the car, that was a red flag.
4. 4Is it a red flag if a new friend never lets you meet their other friends?
5. 5The sudden silence in the team chat was a red flag that something had gone wrong.

语法

可数：a red flag，复数为 red flags。常用在 be、see 或 raise 之后。