Had better

[BobK]

Does anyone really understand this structure? To be honest, it escapes me.

It's pretty old, presumably like 'I'd rather', which derives not from would rather (which some people say nowadays) but from had rather: of two options, I gave more weight to one.

As to the negative, I prefer the version my son coined many years ago: I'd bettern't

[Tdol]

It'll probably catch on.

[ALI_E]

i want to know after had better the verb should be gerend or infinitive
which example is correct
example:I had better study , I had better to study, or I had better studying

[Tdol]

I had better study.

[matilda]

but finally, which one is the best answer to this question, dear moderator?

[BobK]

but finally, which one is the best answer to this question, dear moderator?

Which question, Matilda? Tdol answered it, and his answer is unquestionably right: I had better study - no gerund, no 'to', a bare infinitive.

b

[MikeNewYork]

I had better study.

To answer your initial question, IMO, "had better" is a modal idiom. This is why we can't use the contraction "hadn't better".

[BobK]

... we can't use the contraction "hadn't better".

Well you all can't.

b

[MikeNewYork]

Well you all can't.

b

Do you?

[BobK]

Do you?

I think so, though maybe it's a regional variant (northern ) - anyway, it's quite widespread now (perhaps because of the BBC's decision to allow newsreaders and continuity announcers to keep their regional accents).

b