vain [veɪn]

以下由轻松背单词网站提供

adj.徒劳的，徒然的，无效的，空虚的，自负的

unsuccessful or useless ; of no value

It was in vain that we tried to find his mother. 我们百般设法找他的母亲，但毫无结果。
He's very vain of his abilities. 他对于自己的能力很自负。