lost cause

n. 注定要失败的努力(或行动)

例句与用法：

It is a pity (that) he lost so much money.

他损失这么多钱，真是遗憾。

He is hunting for his lost book.

他正在寻找一本丢失的书。

It's surprising: they lost!

他们竟然失败了，真没想到！

She looked out of the window, sighing for her lost youth.

她看着窗外，为她失去的青春而惋惜。

详细释义：

ph.

败局已定的事(或主张)