a wolf in sheep's clothing

US /ə wʊlf ɪn ʃiːps ˈkloʊðɪŋ/
UK /ə wʊlf ɪn ʃiːps ˈkloʊðɪŋ/
"a wolf in sheep's clothing" picture
1.

披著羊皮的狼

a person who appears friendly or harmless but is actually dangerous or malicious

:
Be careful of him; he's a wolf in sheep's clothing.
小心他;他是披著羊皮的狼
The new manager seemed nice at first, but he turned out to be a wolf in sheep's clothing.
新經理一開始看起來很好,但他原來是披著羊皮的狼