Should

The modal verb should is used in the following ways:

to talk about moral obligation. Compare ought to on Ought to.

They should do what you suggest.
People should report this sort of thing to the police.
She suggested we should visit Aunty Irene more often.
Rob insisted that we should think of others before ourselves.

to give advice or instructions.

You should undo the top screws first.
You should keep your credit card separate from your chequebook.

to suggest that something follows on logically from what has just been said.

They left here at 6 o’clock, so they should be home now.

to show politeness in a conditional clause. This use is used in formal written communication.

If you should decide to go, please contact us.
Should you need more information, please call the manager.

Should can be used with the main verb after certain set expressions such as, it is a pity that, it is odd that, I am sorry/surprised that. This is a more formal use than the same expression without should.

It’s a pity that this should happen.
I was quite surprised that he should be doing a job like that.

Should + the perfect form of the main verb can be used to express regret about something that was done or not done. Compare with ought to.

He should have stopped at the red light.
You should have told me you were ill.

When changing sentences from direct to reported speech, should does not change.

Anna said that I should try to relax more.

In formal English, should can be used with I or we in conditional clauses, instead of the more common would. This form is usually, but not always, found together with an if clause.

I should love to visit Peru if I had the money.
I should be very cross if they didn’t give me a certificate.
We should hate to miss the play.

In this sense, would is more common in modern spoken English.

I would love to visit Peru.
I would be very cross if they didn’t give me a certificate.
We would hate to miss the play.

should
The contracted negative form is:	shouldn’t.