“前功尽弃”常见的英文表达有 “all one's previous efforts are wasted” 、“all the previous work comes to nothing” 或者更简洁的 “lose all one's previous gains” 。
以下是一些例句：
If you give up now, all your previous efforts are wasted. （如果你现在放弃，就会前功尽弃。）
After months of hard work, a small mistake could make all the previous work come to nothing. （经过数月的努力，一个小错误就可能让之前所有的工作前功尽弃。）
Don't let this setback make you lose all your previous gains. （别让这次挫折让你前功尽弃。）