Should ( 1 )

 You should do something = it is a good thing to do or the right thing to do. You can use should to give advice or to give an opinion:

You look tired. You should go to bed.

We often use should with I think / I don’t think / Do you think…?:

I don’t think you should work so hard.

You shouldn’t do something = it isn’t a good thing to do:

You shouldn’t believe everything you read in the newspapers.

Should is not as strong as must:

You should apologise. ( = it would be a good thing to do )

You must apologise. ( = you have no alternative )

We also use should when something is not right or what we expect. For example:

I wonder where Liz is. She should be here by now. ( = she isn’t here yet ,and this is not normal)

We use should to say that we expect something to happen:

She’s been studying hard for the exam, so she should pass. ( = I expect her to pass )

You should have done something = you didn’t do it but it would have been the right thing to do:

It was a great party last night. You should have come. Why didn’t you? ( = you didn’t come but it would have been good to come )

She shouldn’t have been listening to our conversation. It was private.

Compare should ( do ) and should have ( done ) :

You look tired. You should go to bed now.

You went to bed very late last night. You should have gone to bed earlier.

Ought to…

You can use ought to instead of should in the following sentences. Note that we say ‘ought to do…’ ( with to ) :

Do you think I ought to apply for this job? ( = Do you think I should apply…? )

Jack ought not to go to bed so late. ( = Jack shouldn’t go… )

It was a great party last night. You ought to have come.

She’s been studying hard for the exam, so she ought to pass.