do、does、did的用法（强调语气,意思为的确、确实时)为什么在第三人称时does后的动词用原型

I do like reading books.
He does plays football well.
You did came late yesterday.
do/does/did 助动词，后面用动词原形

这个用法并不是书面用语,是比较口语化的英语.
所以在语法上并不需要遵从那些既定的原则,如果想这么用记住就好.
在口语交流时候你即时说了 I did play with her,instead of I did played with her.语言的效果上也是一样的.非要理解成助词也可以.