百无一失 without a single mistake
Explanation
形容做事非常有把握，绝对不会出错。
Describes something done with absolute certainty and without error.
Origin Story
话说唐朝时期，有一位名叫李白的著名诗人，他文采斐然，才思敏捷，在诗歌创作方面有着非凡的天赋。有一天，皇帝要他写一首庆祝新年到来的诗歌，这可是关系到国家盛世景象的重大事件，容不得半点马虎。李白深知此诗的重要性，他决定要做到完美无缺，绝不能出现任何差错。他闭门谢客，潜心创作，日夜苦思冥想，反复斟酌每一个字词，力求做到精益求精。经过几天的辛勤努力，他终于完成了一首气势磅礴、意境深远的诗歌，这首诗不仅赞美了新年新气象，也表达了对国家繁荣昌盛的祝福。皇帝看了这首诗后，龙颜大悦，对李白的才华赞赏有加。这首诗也流传至今，成为了千古名篇。
During the Tang Dynasty, there was a famous poet named Li Bai, known for his elegant style and sharp wit. One day, the emperor ordered him to write a poem to celebrate the New Year, a matter of great importance for the image of the flourishing empire. Li Bai knew the significance of this task and decided to create a flawless poem without any mistakes. He shut himself away from visitors and devoted himself to writing, contemplating day and night, carefully considering each word to achieve perfection. After several days of hard work, he finally completed a magnificent and profound poem that celebrated the New Year's spirit and expressed wishes for the prosperity of the country. The emperor was overjoyed and praised Li Bai's talent. This poem was passed down through generations and remains a famous classic.
Usage
用于形容做事很有把握，绝对不会出错。
Used to describe something done with absolute certainty and without error.
Examples
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他的计划周密，百无一失。
tā de jìhuà zhōumì, bǎi wú yī shī
His plan was meticulous, without a single mistake.
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只要你认真准备，考试百无一失。
zhǐyào nǐ rènzhēn zhǔnbèi, kǎoshì bǎi wú yī shī
As long as you prepare carefully, the exam will be a sure success.