Must mustn’t have to don’t have to – summary Practice Tests with A2 Grammar Rules & Examples

Must, Mustn't, Have To, Don't Have To – Summary

In English, we use must, mustn't, have to, and don't have to to talk about rules, obligations, and things that are necessary or not necessary. These four expressions look similar, but they have very different meanings. If you mix them up, you can say something completely wrong!

Let's look at a simple situation first:

Marco is a new student at school. His teacher gives him the rules:

• "You must arrive on time." (It is very important. It is a rule.)
• "You mustn't use your phone in class." (It is forbidden. Don't do it!)
• "You have to wear a uniform." (It is a school rule. It is necessary.)
• "You don't have to bring a dictionary." (It is not necessary. It is your choice.)

Now let's learn each one step by step.

Must – Strong Obligation or Rule

We use must when something is very important or necessary. The speaker (or a rule) says it is required. We often use must for personal feelings about what is important, or for official rules.

Form:
Subject + must + base verb

Examples:

• You must wash your hands before eating.
• She must take her medicine every day.
• We must be quiet in the library.
• I must remember to call my mum.

Important: The verb after must does not change. We always use the base form of the verb (the infinitive without "to").

Subject	Must	Base Verb	Example
I	must	go	I must go now.
You	must	stop	You must stop here.
He / She / It	must	wear	He must wear a helmet.
We	must	leave	We must leave early.
They	must	finish	They must finish the work.

Note: Must is a modal verb. A modal verb is a special helping verb. Modal verbs do not have an -s in the third person (he/she/it). We say "She must go", not ~~"She musts go"~~.

Mustn't – Prohibition (It Is Forbidden)

Mustn't is the short form (contraction) of must not. We use it when something is forbidden or not allowed. It means: Do not do this. It is against the rules.

Form:
Subject + mustn't + base verb

Examples:

• You mustn't run near the swimming pool. (It is dangerous and not allowed.)
• Students mustn't copy in the exam. (It is against the rules.)
• You mustn't park here. (It is forbidden.)
• She mustn't eat nuts – she is allergic.

Contraction:

must not → mustn't

Both forms are correct. Mustn't is more common in speaking. Must not is more common in writing or for extra emphasis.

Full Form	Contraction	Example
must not	mustn't	You mustn't touch that.
must not	mustn't	He mustn't be late.
must not	mustn't	We mustn't forget our passports.

Have To – External Obligation (A Rule From Outside)

We use have to when something is necessary because of an external rule – a rule made by someone else, like a law, a school rule, or a workplace rule. The speaker does not make the rule; the rule already exists.

Form:
Subject + have to / has to + base verb

Important: With he, she, and it, we use has to (not have to).

Examples:

• I have to show my passport at the airport. (It is the law.)
• She has to wear a uniform at work. (It is her company's rule.)
• We have to pay for the ticket. (It is required.)
• He has to take a test to get his driving licence.

Subject	Have To / Has To	Base Verb	Example
I	have to	work	I have to work on Saturday.
You	have to	sign	You have to sign here.
He / She / It	has to	wear	She has to wear a helmet.
We	have to	leave	We have to leave by 8.
They	have to	pay	They have to pay a fine.

Don't Have To – No Obligation (It Is Not Necessary)

We use don't have to when something is not necessary. Nobody requires you to do it. You can do it if you want, but you don't need to. It is your choice.

Form:
Subject + don't have to / doesn't have to + base verb

Important: With he, she, and it, we use doesn't have to.

Examples:

• You don't have to come to the party. (It is your choice.)
• She doesn't have to cook tonight – we have leftovers.
• I don't have to start work until 10 o'clock.
• They don't have to wear a tie at this restaurant.

Subject	Don't / Doesn't Have To	Base Verb	Example
I	don't have to	go	I don't have to go today.
You	don't have to	hurry	You don't have to hurry.
He / She / It	doesn't have to	come	He doesn't have to come.
We	don't have to	pay	We don't have to pay.
They	don't have to	wait	They don't have to wait.

Important Differences – The Big Summary Table

This is the most important part of the lesson. Look at the meanings carefully. Mustn't and don't have to are completely different!

Expression	Meaning	Example
must	It is necessary. Very important obligation.	You must wear a seatbelt.
mustn't	It is forbidden. Do NOT do this.	You mustn't drink and drive.
have to / has to	It is necessary because of an external rule.	She has to show her ID.
don't have to / doesn't have to	It is NOT necessary. You have a choice.	You don't have to wear a tie.

Must vs Have To – What Is the Difference?

Both must and have to talk about obligation, but there is a small difference:

• We use must when the speaker thinks something is important or when it is a personal obligation.
  Example: I must phone my dad. (I think it is important.)
• We use have to when there is an external rule – a law or a rule from someone else.
  Example: I have to pay tax. (It is the law. I don't have a choice.)

In everyday spoken English, many people use must and have to with the same meaning and this is perfectly acceptable at A2 level. The difference is small and not always important.

Mustn't vs Don't Have To – The Most Important Difference

This is the most common mistake for English learners. These two expressions are completely opposite in meaning.

Mustn't = It is forbidden. Do NOT do it.
You mustn't tell anyone. (Do not tell anyone! It is a secret.)

Don't have to = It is not necessary. You can choose.
You don't have to tell anyone. (You can tell people if you want, but it is not necessary.)

Look at these two sentences. The difference is very big:

• You mustn't eat that. (Stop! Don't eat it! It is forbidden.)
• You don't have to eat that. (It is fine. Eat it if you want, but you don't need to.)

Common Mistakes

❌ She musts go to school.
✅ She must go to school. (Modal verbs do not add -s for he/she/it.)

❌ You don't have to touch the fire – it's dangerous!
✅ You mustn't touch the fire – it's dangerous! (Forbidden = mustn't, not don't have to.)

❌ He must to wear a uniform.
✅ He must wear a uniform. (After must, use the base verb without "to".)

❌ She have to work on Sundays.
✅ She has to work on Sundays. (With he/she/it, use has to.)

❌ You doesn't have to shout.
✅ You don't have to shout. (With you/I/we/they, use don't have to.)

❌ I mustn't to be home by 10.
✅ I must be home by 10. (Use must + base verb, not must + to + verb.)

❌ They don't have to drive fast – the speed limit is 30!
✅ They mustn't drive fast – the speed limit is 30! (Speed limits are rules = mustn't, not don't have to.)

Must, Mustn't, Have To, Don't Have To – Quick Summary

Here is a quick review of everything we have learned:

• Must = strong obligation or necessity (the speaker decides it is important).
• Mustn't = prohibition – it is forbidden, do not do it.
• Have to / Has to = obligation from an external rule or law.
• Don't have to / Doesn't have to = no obligation – it is not necessary, you have a choice.

Remember the most important rule: mustn't and don't have to are NOT the same. Mustn't means forbidden. Don't have to means not necessary.

After must and mustn't, always use the base verb (no "to", no -s ending).

With have to in the third person (he/she/it), always use has to and doesn't have to.

Now practise must, mustn't, have to, and don't have to in the exercises below.