道貌岸然
Look as if butter would not melt in one's mouth.
eg:The girl looks as if butter would not melt in her mouth when she sits next to her teacher.
中英俚语俗语来源:续仙传:“李延情景恬檐,道貌秀异。”
同义词:一本正经Have a serious look.
反义词:贼眉鼠眼 Have the brand of a villain in one's looks.