无孔不入 Ubiquitous
Explanation
形容事物或人能钻进任何空隙，比喻能利用一切机会达到目的。
To describe something or someone that can penetrate any gap, as a metaphor for the ability to use any opportunity to achieve a goal.
Origin Story
有一个小偷，他非常狡猾，能从任何地方找到突破口，于是他给自己起了个绰号叫“无孔不入”。一天，他听说富豪王员外家收藏了许多珍宝，于是决定去偷。王员外家戒备森严，大门上装了坚固的铁门，窗户上安了厚厚的铁栅栏，院墙高耸，还养了凶猛的看门狗，看起来是固若金汤，无懈可击。但无孔不入的小偷却丝毫不惧。他仔细观察了王员外家的每一个角落，终于发现了一个不起眼的小漏洞，原来是院墙下的一块砖头松动了。他利用一根小铁棍，轻轻地撬开砖头，从缝隙中钻进了院子。他轻手轻脚地躲避着看门狗，绕过层层守卫，最终找到了珍宝库，成功地盗走了里面的财宝。王员外得知此事后，气得暴跳如雷，但再怎么追查，也找不到小偷的踪迹。于是，大家就说，这个小偷真是“无孔不入”，再严密的防范也奈何不了他。
There was a thief who was very cunning and could find a way in from any place, so he gave himself the nickname
Usage
这个成语常用来形容一些人或事物能利用一切机会达到目的，非常狡猾。
This idiom is often used to describe people or things that can use any opportunity to achieve their goals, very cunning.
Examples
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他的说辞无孔不入，让人防不胜防。
ta de shuo ci wu kong bu ru, rang ren fang bu sheng fang.
His arguments are pervasive and impossible to defend against.
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这些谣言无孔不入，影响了大家的正常生活。
zhe xie yao yan wu kong bu ru, ying xiang le da jia de zheng chang shenghuo.
These rumors are ubiquitous and affect everyone's normal life.
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商业广告无孔不入，真是无处不在。
shang ye guang gao wu kong bu ru, zhen shi wu chu bu zai.
Commercial advertisements are ubiquitous and are truly everywhere.