had better是情态动词吗?他的否定和疑问句如何构成?

是情态动词
hadn't better
had +主语＋better
Had better意为“最好”,后接不带to的不定式.如：
— We had better go now.
— Yes,we had (we'd better / we had better).
Hadn't we better stop now?(Had we better not stop now?)
I think I'd better be going.（用于进行时态,表“最好立即”）
You had better have done that.（用于完成时态,表未完成动作）
注：①had best与had better同意,但较少用.②You had better … 用于同辈或小辈,对长辈不可用.
3.Would rather意为“宁愿”,表选择,后接不带to的不定式.如：
I'd rather not say anything.
Would you rather work on a farm?
— Wouldn't you rather stay here?
— No,I would not.I'd rather go there.
由于would rather表选择,因而后可接than.如：
I would rather work on a farm than in a factory.
I would rather watch TV than go to see the film.
I would rather lose a dozen cherry trees than that you should tell me one lie.
I'd rather you didn't talk about this to anyone.（句中的'd rather不是情态动词,would在此是表愿望的实义动词）