Diplomatic efforts at peace-making have so far proved unavailing.调停争端的外交努力到目前为止被证明是徒劳的。He died after a brave but unavailing fight against a terminal illness.在与绝症进行了一番勇敢但却徒劳的抗争之后，他还是去世了。Efforts to reach the people named in the report proved unavailing.想办法联系过报告中提到的那些人，但都没有成功。