一气呵成 do something in one go
Explanation
这个成语形容做事的时候，思路清晰，不间断地完成，比喻做事快速而顺利。
This idiom describes doing something with a clear mind, without interruption, figuratively meaning quickly and smoothly.
Origin Story
古代有一位著名的书法家，他笔法精妙，写字时龙飞凤舞，一气呵成，令人叹为观止。一天，他接到了一位朋友的邀请，请他为一座新修建的寺庙写一块匾额。书法家欣然应允，来到寺庙后，他看到寺院规模宏伟，气势雄壮，便心生豪迈之情，挥笔写下了“万寿山”三个大字。三个字笔力遒劲，气势磅礴，一气呵成，仿佛将整座山岳都凝聚在其中，令人叹为观止。寺庙主持见此书法，喜不自胜，连声称赞书法家是“天下一绝”。这便是“一气呵成”的典故。
In ancient times, there was a famous calligrapher who was known for his exquisite penmanship. His writing was so fast and elegant that people were amazed. One day, he received an invitation from a friend to write a plaque for a newly built temple. The calligrapher readily agreed, and when he arrived at the temple, he saw that the temple was grand and imposing, and he felt a sense of grandeur. He picked up his brush and wrote the three large characters
Usage
这个成语多用于形容文章的写作，也可以形容做事的能力，比如：他写文章一气呵成，文笔流畅。
This idiom is often used to describe the writing of an article, but it can also describe the ability to do something, for example: He wrote the article in one go, his writing is smooth.
Examples
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他一口气写完了这篇文章，真是～
ta yi kou qi xie wan le zhe pian wen zhang, zhen shi yi qi he cheng
He wrote the article in one go, it's really a feat.
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这项工作必须～，不能拖延
zhe xiang gong zuo bi xu yi qi he cheng, bu neng tuo yan
This work must be done, there is no delay