a fish out of water 不合群的人
A person who does not fit in with other people; someone not in their proper environment.
Visiting a foreign country last year I went to a party just wearing a sweater, but everyone else was wearing formal clothing, and nobody spoke my language, so I really felt like a fish out of water.
去年,在造访某国时,我穿着一件毛衣就去参加聚会,但别人全都穿着正式服装,又没有人说我的语言,因此我感到与他们实在格格不入。