功亏一篑 Success ruined by one basket of earth
Explanation
比喻事情做到将近成功的时候，因为缺少最后一点努力而失败。
It is used to describe a situation where one is on the verge of success, but fails in the end due to lack of effort.
Origin Story
很久以前，有一个非常勤奋的年轻人，他立志要建一座高耸入云的山峰。他日复一日，年复一年地搬运土石，这座山也渐渐地拔地而起，越来越高。眼看着这座山就要建成了，只剩下一筐土就能完成了，可是年轻人却因为一时疏忽，没有及时补充最后一筐土，导致这座山最终没有建成。年轻人后悔莫及，但他明白了一个道理：任何事情，都必须坚持到底，否则很容易功亏一篑。
Long ago, there was a very diligent young man who set his mind to build a towering mountain peak. Day after day, year after year, he transported earth and stones, and the mountain gradually rose from the ground, getting taller and taller. As the mountain was about to be completed, only one basket of earth was needed, but the young man, due to a momentary oversight, failed to add the last basket of earth, resulting in the mountain never being completed. The young man regretted it deeply, but he learned a valuable lesson: In everything, one must persevere to the end; otherwise, one easily fails just before success.
Usage
多用于形容做事认真，但因缺乏最后一点努力而失败的情况。
It is often used to describe the situation where one works diligently but fails due to lack of final effort.
Examples
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他眼看就要成功了，没想到功亏一篑，真是可惜！
ta yan kan jiu yao chenggong le, meixiang gong kui yi kui, zhen shi kexi
He was about to succeed, but unfortunately, he failed at the last moment. What a pity!
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创业维艰，稍有不慎就会功亏一篑。
chuangye weijian, shao you busheng jiu hui gong kui yi kui
Starting a business is difficult, and one can easily fail if one is not careful.