Which Modal Verb Expresses An Obligation Imposed By The Speaker?

Past – Must has no past form. Instead, we use had to to express past obligations: When I was at primary school, I had to wear a uniform. We had to start all over again. : Modals to express obligation: MUST, HAVE (GOT) TO

What is the modal verb for obligation?

Modal verbs part 2 – obligation :must, have to, should and ought to. There are two types of modal verbs of obligation ; those that primarily express a firm obligation or necessity – must and have to. those that express a recommendation or moral obligation – should and ought to.

Is must have done a modal verb?

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Present	Positive	Negative
have to / don’t have to	strong obligation (possibly from outside) Children have to go to school. (sometimes ‘have got to’)	no obligation I don’t have to work on Sundays. You don’t have to eat anything you don’t like.
must / mustn’t	strong obligation (possibly based on the speaker’s opinion) I must study today.	negative obligation You mustn’t smoke here.
should / shouldn’t	mild obligation or advice You should save some money.	mild negative obligation or advice You shouldn’t smoke so much.

Be careful about the difference between mustn’t and don’t have to ! Mustn’t means it’s not allowed, or it’s a bad idea:

You mustn’t eat so much chocolate, you’ll be sick

Don’t have to means you don’t need to do something, but it’s fine if you want to do it:

I don’t have to get up early at the weekend(of course, if I want to get up early, that’s fine, but I can stay in bed if I want).

Past	Positive	Negative
had to / didn’t have to	obligation in the past I had to wear a school uniform when I was a child.	no obligation in the past We didn’t have to go to school on Saturdays.
must*	changes to ‘had to’	–
should have + pp / shouldn’t have + pp	a past action which didn’t happen: the advice / regret is too late You should have gone to bed earlier, now you have missed the train.	a past action which didn’t happen: the advice / regret is too late You shouldn’t have taken that job., it was a bad idea.

Remember ‘must have done ‘ is a modal verb of deduction or speculation, not obligation in the past. For example: Julie must have left. Her coat’s not here. See modals of probabilty for more information.

Click here to download this explanation as a pdf. Click here for modal verbs of obligation exercise 1. Click here for all the modal verbs exercises.

Is’must have done’a modal verb?

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Some of our partners may process your data as a part of their legitimate business interest without asking for consent. To view the purposes they believe they have legitimate interest for, or to object to this data processing use the vendor list link below. The consent submitted will only be used for data processing originating from this website.

If you would like to change your settings or withdraw consent at any time, the link to do so is in our privacy policy accessible from our home page.

Present	Positive	Negative
have to / don’t have to	strong obligation (possibly from outside) Children have to go to school. (sometimes ‘have got to’)	no obligation I don’t have to work on Sundays. You don’t have to eat anything you don’t like.
must / mustn’t	strong obligation (possibly based on the speaker’s opinion) I must study today.	negative obligation You mustn’t smoke here.
should / shouldn’t	mild obligation or advice You should save some money.	mild negative obligation or advice You shouldn’t smoke so much.

Be careful about the difference between mustn’t and don’t have to ! Mustn’t means it’s not allowed, or it’s a bad idea:

You mustn’t eat so much chocolate, you’ll be sick

Don’t have to means you don’t need to do something, but it’s fine if you want to do it:

I don’t have to get up early at the weekend(of course, if I want to get up early, that’s fine, but I can stay in bed if I want).

Past	Positive	Negative
had to / didn’t have to	obligation in the past I had to wear a school uniform when I was a child.	no obligation in the past We didn’t have to go to school on Saturdays.
must*	changes to ‘had to’	–
should have + pp / shouldn’t have + pp	a past action which didn’t happen: the advice / regret is too late You should have gone to bed earlier, now you have missed the train.	a past action which didn’t happen: the advice / regret is too late You shouldn’t have taken that job., it was a bad idea.

Remember ‘must have done ‘ is a modal verb of deduction or speculation, not obligation in the past. For example: Julie must have left. Her coat’s not here. See modals of probabilty for more information.

Click here to download this explanation as a pdf. Click here for modal verbs of obligation exercise 1. Click here for all the modal verbs exercises.

How do you use the word obligation in a sentence?

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Some of our partners may process your data as a part of their legitimate business interest without asking for consent. To view the purposes they believe they have legitimate interest for, or to object to this data processing use the vendor list link below. The consent submitted will only be used for data processing originating from this website.

If you would like to change your settings or withdraw consent at any time, the link to do so is in our privacy policy accessible from our home page.

Present	Positive	Negative
have to / don’t have to	strong obligation (possibly from outside) Children have to go to school. (sometimes ‘have got to’)	no obligation I don’t have to work on Sundays. You don’t have to eat anything you don’t like.
must / mustn’t	strong obligation (possibly based on the speaker’s opinion) I must study today.	negative obligation You mustn’t smoke here.
should / shouldn’t	mild obligation or advice You should save some money.	mild negative obligation or advice You shouldn’t smoke so much.

Be careful about the difference between mustn’t and don’t have to ! Mustn’t means it’s not allowed, or it’s a bad idea:

You mustn’t eat so much chocolate, you’ll be sick

Don’t have to means you don’t need to do something, but it’s fine if you want to do it:

I don’t have to get up early at the weekend(of course, if I want to get up early, that’s fine, but I can stay in bed if I want).

Past	Positive	Negative
had to / didn’t have to	obligation in the past I had to wear a school uniform when I was a child.	no obligation in the past We didn’t have to go to school on Saturdays.
must*	changes to ‘had to’	–
should have + pp / shouldn’t have + pp	a past action which didn’t happen: the advice / regret is too late You should have gone to bed earlier, now you have missed the train.	a past action which didn’t happen: the advice / regret is too late You shouldn’t have taken that job., it was a bad idea.

Remember ‘must have done ‘ is a modal verb of deduction or speculation, not obligation in the past. For example: Julie must have left. Her coat’s not here. See modals of probabilty for more information.

Click here to download this explanation as a pdf. Click here for modal verbs of obligation exercise 1. Click here for all the modal verbs exercises.