万全之策 Foolproof plan
Explanation
“万全之策”指的是非常周密、没有漏洞的计划或策略。它强调计划的完善性，能够考虑到各种情况，确保万无一失。
“万全之策” means a very thorough and flawless plan or strategy. It emphasizes the completeness of the plan, which takes into account all contingencies and ensures foolproof success.
Origin Story
三国时期，曹操与袁绍在官渡对峙，战况焦灼。曹操深知袁绍兵力雄厚，粮草充足，若正面交锋，必难取胜。于是，曹操决定采用“万全之策”，先以虚张声势之计，让袁绍以为他粮草不足，不得不退兵。接着，曹操暗中派人袭击袁绍的粮道，并利用火攻，大败袁绍军队。最终，曹操以少胜多，取得官渡之战的胜利。
In the Three Kingdoms period, Cao Cao confronted Yuan Shao at Guandu, and the battle situation was tense. Cao Cao knew that Yuan Shao had a strong army and ample supplies, and a direct attack would be difficult to win. Therefore, Cao Cao decided to use a “万全之策”, first using a bluff to make Yuan Shao think that he was short of supplies and had to retreat. Then, Cao Cao secretly sent people to attack Yuan Shao's supply lines and used fire attacks to defeat Yuan Shao's army. Finally, Cao Cao won the battle of Guandu with fewer troops.
Usage
“万全之策”通常用来形容非常周密的计划或策略，用来确保万无一失。它可以用于各种场景，例如工作、生活、学习等。
“万全之策” is usually used to describe a very thorough plan or strategy, used to ensure that nothing goes wrong. It can be used in a variety of situations, such as work, life and study.
Examples
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我们必须想出一个万全之策，确保万无一失。
wǒ men bì xū xiǎng chū yī ge wàn quán zhī cè, què bǎo wàn wú shī.
We must come up with a foolproof plan to ensure nothing goes wrong.
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面对困难，我们要制定万全之策，才能顺利解决问题。
miàn duì kùn nan, wǒ men yào zhì dìng wàn quán zhī cè, cái néng shùn lì jiě jué wèn tí.
In the face of difficulties, we must make a comprehensive plan to solve the problem smoothly.