前功尽弃

chéng gōng de xī wàng bù dà hěn kě néng qián gōng jìn qì

成功的希望不大，很可能前功尽弃。

There is small chance of success, and you risk all you have gained.

dà bà yī dìng yào zài yǔ jì kāi shǐ qián hé lǒng fǒu zé jiù huì qián gōng jìn qì

大坝一定要在雨季开始前合拢，否则就会前功尽弃。

The dam must be closed before the rainy season sets in, or all our labour will be lost.

rú guǒ jiù cǐ zhǐ bù kě néng huì qián gōng jìn qì

如果就此止步，可能会前功尽弃。

If we stop there, all our previous efforts will be wasted.

zhè ge kě pà de cuò wù ràng wǒ men qián gōng jìn qì

这个可怕的错误让我们前功尽弃。

This terrible mistake undid all our efforts.