you did better后加什么？

you did better意为你最好做某事；

youd better后直接加动词原形；

实际上，had better do sth是固定搭配，意思是最好做某事，因为bad better是情态动词，而情态动词的后面接动词原因，所以had better的后面就接do sth。

we had better hurry or we will miss the train。

我们最好快点，否则就赶不上火车了

now that you are here，you had better stay。

既然你已经来了，最好还是住下

you had better go to hospital at once。

你最好还是马上去医院

you had better go over the lesson。

你最好复习功课。