a red flag

意思

a sign that something may be wrong or dangerous

可能出問題或有危險的跡象.

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.

文法

可數：a red flag，複數為 red flags。常用在 be、see 或 raise 之後。