ought to ,应该,客观上的应该,The cake ought to be good—I used the best ingredients.蛋糕应该是好的——我用了最好的配料.
should 主观上的应该,we should study hard.
had better,最好,Perhaps you and I had better change over; you are more experienced.也许我们的工作还是对换一下好,你比我更有经验.
must,必须,不得不 ,也是主观上的.程度比should强多了.we must study hard.
have to ,是客观上的.不得不.Please be quiet.I have to study the book for a test tomorrow.请不要说话了,明天要考试,我得看书.
希望对你有用.