Look at this example:

• Jane had to wait an hour for a bus.

Had to wait means that Jane waited because no bus came for an hour.

We use had to to talk about something that somebody did because it was necessary.

If somebody did not do something because it was not necessary, we use didn’t have to:

• I didn’t have to work last weekend. (= I didn’t work because it wasn’t necessary.)

The question form is did … have to:

• Did you have to work last weekend?

Now consider this situation:

We use should have + past participle (gone, done, etc.) to say that something which did not happen was the correct or best action. We can also use should have + past participle to criticise somebody. Look at this example:

We use shouldn’t have + past participle (gone, done, etc.) to say that something which did happen was not the correct action:

• I shouldn’t have eaten all that blue cheese. I’ve got stomach ache. (= I ate the blue cheese but it was not a good thing to do.)
• George shouldn’t have left the gate open. (= He left it open, which wasn’t the correct thing to do.)