呢個活用同其他活用（現代文中普遍存在嘅五段同上、下一段，同埋古語中普遍存在嘅四段同上一、上二、下一、下二，甚至係唔規則嘅ナ行、ラ行、サ行）唔同嘅地方在於，カ変淨係用來描述「來る」呢一個詞本身嘅唔規則。解究「來る」變得不規則嘅原因係因為佢係日常用語，而使用頻度好高嘅詞即使喺歷史上文法甚至音位規則發生變化時，好多情況都都唔願意隨之發生形態上嘅變化。
The difference between this and other uses (the five paragraphs that are common in modern texts is the same as the previous and the next paragraph, and the four paragraphs that are common in ancient languages, and the four paragraphs that are common in ancient languages, and the upper two, the next two, the next, and even the irregular ナ行, ラ行, and サ行) is that カ変 is only used to describe the irregularity of the word "来る" itself. The reason why "来る" has become irregular is that it is a daily language, and words that are used frequently are reluctant to change morphology in many cases, even when grammar and even phonemic rules have changed in history.