should
- ought to
expectation
You use should or ought to to say that you expect something to happen.
We should be there by dinner time.
It ought to get easier with practice.
You use should or ought to with have and an -ed participle to say that you expect something to have happened already.
You should have heard by now that I'm O.K.
It's ten o'clock, so they ought to have reached the station.
You also use should or ought to with have and an -ed participle to say that something was expected to happen, but did not happen.
Bags which should have gone to Rome were sent to New York.
The project ought to have finished by now.
Be careful
You must use have and an -ed participle in sentences like these. Don't say, for example, ‘The project ought to finish by now’.
You must use have and an -ed participle in sentences like these. Don't say, for example, ‘The project ought to finish by now’.
moral rightness
You use should or ought to to say that something is morally right.
Crimes should be punished.
I ought to call the police.
giving advice
You can say you should or you ought to when you are giving someone advice.
I think you should go see your doctor.
I think you ought to try a different approach.
negative forms
Should and ought to have the negative forms should not and ought not to.
This should not be allowed to continue.
They ought not to have said anything.
The not is not usually pronounced in full. When you write down what someone says, you write shouldn't or oughtn't to.
You shouldn't dress like that, Andrew.
They oughtn't to mention it.
When you make a negative statement with ought in American English, you can omit to:
You oughtn't answer the door without your shirt on.