vainKK [ven] /veɪn/发音形容词1自负的、虚荣的、爱慕虚荣的贬义He is so vain that he checks his reflection in every window.他非常自负,经过每片玻璃都要照一下自己。2徒劳的、无效的、白费的They made a vain attempt to save the flooded basement.他们试图抢救淹水的地下室,但徒劳无功。3空虚的、无价值的正式His promises turned out to be nothing but vain words.他的承诺到头来只是空话。片语1白费、徒然、枉然We waited three hours in vain for the delayed train.我们白等了三个小时,那班误点的火车始终没来。用这个字练口说→相关片语in vain