无隙可乘 no loophole to exploit
Explanation
指没有空子可以钻，形容防御严密，没有弱点。
It means there is no loophole to exploit, describing tight defense and no weaknesses.
Origin Story
话说唐朝时期，边关告急，敌军来势汹汹，准备攻打我大唐边境重镇——玉门关。玉门关守将李将军久经沙场，深知敌军狡诈，他下令全军戒备，严防死守。他仔细检查城墙，加固城防，甚至连细小的缝隙都不放过，做到无懈可击，无隙可乘。敌军数次试图进攻，都被守军顽强抵抗，最终无功而返。李将军以其卓越的军事才能和严密的防卫，保卫了玉门关的安全，为大唐的边境安宁立下了汗马功劳。 几十年后，李将军的孙子李小将军也成了玉门关的守将，他自幼听闻爷爷的传奇事迹，也决心像爷爷一样，成为一名保家卫国的优秀将领。但李小将军性格轻率，不重视防卫工作，认为敌军不会再攻打玉门关。结果，敌军轻而易举地攻破了城防，李小将军兵败身亡，玉门关陷落。
During the Tang Dynasty, a border crisis occurred, with enemy forces aggressively preparing to attack the important border town of Yu-men Pass. General Li, the commander of Yu-men Pass, a seasoned veteran, understood the enemy's cunning. He ordered full military preparedness and strict defense. He thoroughly inspected the walls, reinforced the defenses, and left no small gaps unchecked, making it impossible for the enemy to find a weakness. The enemy army tried to attack several times but was repelled by the strong resistance. They finally retreated without achieving anything. General Li’s military skills and rigorous defense ensured the safety of Yu-men Pass. Decades later, General Li’s grandson, young General Li, became the commander of Yu-men Pass. He had heard tales of his grandfather's legendary feats and was determined to be a capable defender of the nation. However, Young General Li was careless and neglected defensive work, believing the enemy would not attack Yu-men Pass again. As a result, enemy forces easily breached the defenses, resulting in the young general’s defeat and the fall of Yu-men Pass.
Usage
用于形容防御严密，没有弱点，敌人无法可乘。
Used to describe a tight defense with no weaknesses, offering no point of attack for the enemy.
Examples
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他的计划部署周密，无懈可击，无隙可乘。
tā de jìhuà bǔshù zhōumì, wú xiè kě jī, wú xì kě chéng
His plan was well-deployed, impeccable, and left no room for attack.
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这道题毫无破绽，无隙可乘。
zhè dào tí háo wú pòzhàn, wú xì kě chéng
This question is flawless; there is no weakness to exploit