adj.自负的；徒劳的；无效的；虚荣的
She is vain of her voice. 她自以为她的声音了不起。
They endeavoured to make her happy but in vain. 他们尽量使她快乐，却徒劳无功。
All his father's exhortations were in vain. 他父亲的一切劝告都无效。
We tried in vain to make him change his mind. 我们想使他改变主意，结果是白费心机。
The world had made him extravagant and vain. 世俗使他变得放荡不羁，虚荣自负。
She is so vain that she can't pass a mirror without looking into it. 她好爱虚荣,每经过一面镜子都要照一下。
adv.徒劳地
adj.非常自负的；虚荣心强的
n.极度自负；虚荣
