adj.徒劳的,无效的,无用的;
例句:
His best efforts, however, proved unavailing and the child died.
然而, 他所有的努力都无济于事,女儿还是死了.
All our protests were unavailing.
我们的抗议全部无用.
Their efforts were unavailing.
他们的努力都付诸东流。