look a gift horse in the mouth
US /lʊk ə ɡɪft hɔrs ɪn ðə maʊθ/
UK /lʊk ə ɡɪft hɔrs ɪn ðə maʊθ/

1.
挑剔贈品, 對禮物吹毛求疵
to be ungrateful when receiving a gift or favor by criticizing it
:
•
I know the car isn't new, but don't look a gift horse in the mouth.
我知道車不是新的,但不要挑剔贈品。
•
They offered you a free trip, so don't look a gift horse in the mouth.
他們給你提供了免費旅行,所以不要挑剔贈品。