in vain -用法

in vain

without success；without effect徒劳地；无效地

He passed his life in vain．他虚度了一生。

The drowning man called in vain for help．溺水者求救无门。

All the doctor's efforts were in vain and the man soon died．医生所有的努力都无效，那个人很快就死了。