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.
中英俚語俗語來源:續(xù)仙傳:“李延情景恬檐,道貌秀異。”
同義詞:一本正經(jīng)Have a serious look.
反義詞:賊眉鼠眼 Have the brand of a villain in one's looks.