1、 They made vain attempts to reach the mountaintop、他们几次徒然尝试想攀登山顶。
2、 The police tried in vain to break up the protest crowds、警察企图驱散抗议的人群，但没有成功。
3、 She's very vain about her good looks、她为她那好的容貌而自负。
4、 He is vain of his speech、他对自己的发言很得意。
5、 She is vain and extravagant、她既爱虚荣又奢侈。