Don't( )（看不起）a student only because he has failed in an exam

Don't( )（看不起）a student only because he has failed in an exam
Don't( )（看不起）a student only because he has failed in an exam

Don't( )（看不起）a student only because he has failed in an exam
Don't(look down upon )（看不起）a student only because he has failed in an exam

look down

despise
[disˈpaiz]
vt.
鄙视, 看不起某人(某事)
look down on
看不起(某人)

除了look down 我自认为还可以用laugh at 嘲笑
以前做过这道题