keep a civil tongue in your head
US /kiːp ə ˈsɪv.əl tʌŋ ɪn jʊər hɛd/
UK /kiːp ə ˈsɪv.əl tʌŋ ɪn jʊər hɛd/

1.
言语得体, 说话客气
to speak politely and avoid rude or offensive language
:
•
You need to keep a civil tongue in your head when talking to your elders.
和长辈说话时,你必须言语得体。
•
Even when angry, try to keep a civil tongue in your head.
即使生气,也要努力言语得体。