had better
should
could
would
情态动词
ought to和had better用法详解
ought to+原形动词表示义务、劝告或推测等意义,意思是"应该…".
I am tired.I ought to sit here for a while.
我累了,我应该休息一会儿.
表示否定时,not放在ought之后.在美语中,在否定句中,ought之后的不定词符号to常可省略.
Hey,boy,you oughtn't （to） sleep here.Get up!
嘿,孩子,你不应该躺在这儿.起来!
在美语中,在疑问句中,ought之后的不定词符号to常可省略.
Ought you （to） do it?
你应该这么做吗?
had better只有一种形式,不是表示过去,而是指现在或未来,表示向对方提出劝告或警告.had better+原形不定词表示"最好……".
You had better give up smoking.
你最好把烟戒掉.
had better的否定形式是had better not.
You had better not throw it on the ground.
你最好别把它扔在地上.
had better很少用于疑问句,但有时为了表示忠告或建议而用否定疑问句,这时否定副词not位于主语之后.
Had you better not talk to yourself?
你不要自言自语好不好?