had better not do sth是正确的,to已被省略掉,详细解释请见以下:
had better(常简略为'd better)是一固定词组,had better"最好",用于表示对别人的劝告、建议或表示一种愿望.其用法有以下几点:
一、had better后面必须跟动词原形.
had better后跟动词原形(即不带to的
不定式),构成had better do sth.句型.
这里的had不能用have来替换.如:
You'd better go to hospital at once.你最好立即去医院看病.
Tom,you'd better go there today.汤姆,你最好今天去那儿.
二、主语不论是第几人称,句子不论是什么时态,都要用had better的形式.如:
Now you(he,we) had better listen to the teacher.你(他,我们)现在最好听老师讲.
三、had better的否定式.如:
常用的否定形式是将否定副词not直接放在had better的后面. 此处to已省略,不可加上,如:
You had better not miss the last bus.你最好不要错过末班公共汽车.
You had better not leave for Nanjing the day after tomorrow.你最好后天不要动身去南京.
注意:否定副词not绝不能放在had的后面.如:不能说:You hadn't better go.而应该说:You had better not go.