hold your tongue
US /hoʊld jʊər tʌŋ/
UK /hoʊld jʊər tʌŋ/

1.
保持沉默, 闭嘴
to remain silent and not speak, especially when you want to say something negative or critical
:
•
I had to hold my tongue when my boss made that ridiculous suggestion.
当老板提出那个荒谬的建议时,我不得不保持沉默。
•
It's best to hold your tongue if you don't have anything nice to say.
如果你没有什么好话要说,最好保持沉默。