The main verbs of obligation are: MUST HAVE TO SHOULD+ You must stop here. (obligation)+ I have to stop here. (obligation)-They mustn’t smoke. (prohibition) - He doesn’t have to work on Saturdays. (no

obligation)+ You should do more exercise. (weak obligation)- She shouldn’t work so hard. (weak prohibition)

Remember these things about HAVE TO: 1. Use the infinitive after have to

We have to wear long trousers.

2. The negative means there is no obligation We don’t have to pay to enter. (it’s not necessary)

3. There is a 3rd person form He has to work on Saturdays.

4. You can refer to the past or the future by changing the verb tense. Yesterday, we had to walk, the car didn’t start. = the

past Tomorrow, we will have to walk, the car isn’t working.

= the future

Remember these things about should: Should is used for weak (debil) obligation.

It is used to say something is a good idea or a bad idea e.g. I should do more exercise. (good idea) He shouldn’t smoke so much. (bad idea) We shouldn’t be late. (bad idea) Should we turn left or right?

It is similar to must. There is no to after should and there is no 3rd person.

Allowed to – this means to permit. It is often used with the verb to be and is considered quite formal. Members of the public are not allowed in here.

Can – Used mainly for ability but also for permission and prohibition. You can smoke in here. You can’t touch anything

Ban- this verb has the same meaning as prohibit. It can also be used as a noun. Drinking alcohol is banned. Mobile phones are

banned. There is a ban on alcohol at football matches.

Forbid – This is also similar to prohibit. Picking flowers is forbidden.

Now practice the exercises in this grammar unit.