前功尽弃

前功尽弃 [qián gōng jìn qì]

1. ■ waste all the previous efforts; waste the efforts already made; All labour lost.; All one's labour has been in vain.; All the work one has done is wasted.; All that has been achieved is spoiled.; All one's previous efforts are wasted.; All previous work undone.; All previous work came to naught.; forfeiture of all the former achievements; One's past merits will count for nothing.; The former labour is all wasted.; All the former tasks have been thrown away.:

大坝一定要在雨季开始以前合拢， 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.