had better 相当于一个助动词,它只有一种形式,它后面要跟动词原形。
had better do sth
had better not do sth
例句:
It is pretty cold. You'd better put on my coat.
She'd better not play with the dog.
注意:had better have done sth表示与事实相反的结果,意为"本来最好"。
例句:
You had better have come earlier.