准情态动词had better的用法归纳（五“式”）
1. had better的基本式
had better意为“最好”、“应该”，后接动词原形。如：
You had better set off at once. 你还是马上动身的好。
You'd better be there. 你最好在那里。
You'd better stay at hospital for another few days. 你最好在医院再住几天。
Better have the operation right now. 你最好还是现在就动手术。
2. had better的否定式
通常将not置于had better之后。
We'd better not invite him. 我们最好不要邀请他。
Better not wait for him. 最好不要等他了。
误：You had not better go. 你最好不要去。
误：You had better not to go.
正：You had better not go.
3. had better的疑问式
通常将had置于主语之前。如：
Had we better go now? 我们现在该走了吗？
在否定疑问句或反意疑问句中可将not与had连用。如：
Hadn’t we better go now? 我们是不是现在就去呢?
4. had better+进行式
表示最好马上做某事。如：
I think I’d better be going．我想我最好还是马上走。
You’d better be getting your clothes ready. 你最好马上把衣服准备好。
5．had better+完成式
表示最好做完某事或本该做某事而未做某事。如：
You had better have done that. 你最好把那事做完。
You had better have stayed here. 你本来应该呆在这儿的。