unavailing

Despite hours of effort, their attempts to fix the old radio proved unavailing.

尽管花了几个小时，他们修理那台旧收音机的尝试还是徒劳无功。

用法提示：unavailing 作表语形容词，表示“徒劳的”。

His unavailing search for the missing key made him late for work.

他寻找丢失钥匙的努力毫无结果，导致上班迟到了。

用法提示：unavailing 作定语形容词，修饰 search，表示“毫无结果的”。

She knew that arguing with him would be unavailing, so she stayed silent.

她知道跟他争论是徒劳的，于是保持沉默。

用法提示：unavailing 作表语，说明争论是“无效的、徒劳的”。