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Level 6 (CEFR A2+)

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  1. Lesson 1 | Writing an Informal Email or Letter
    5 Temas
    1 Cuestionario
  2. Lesson 2 | Uses of the gerund
    7 Temas
    3 Cuestionarios
  3. Lesson 3 | Wearing the same clothes every day
    5 Temas
  4. Lesson 4 | I Have to Go
    7 Temas
    4 Cuestionarios
  5. Lesson 5 | You’d better go and see your G.P.
    7 Temas
    4 Cuestionarios
  6. Lesson 6 | Let’s watch a film
    7 Temas
    4 Cuestionarios
  7. Lesson 7 | Writing a review
    5 Temas
  8. Lesson 8 | What would you do?
    6 Temas
    4 Cuestionarios
  9. Lesson 9 |
  10. Lesson 10 |
  11. Lesson 11 |
  12. Lesson 12 |
  13. Lesson 13 |
  14. Lesson 14 |
Lección 4, Tema 3
En Progreso

Lesson 4 – Step 3 – Modals: Obligation – must, mustn’t and have to

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It’s time to learn about the difference between must and have to.

You can watch the video or go straight to the written explanation. You decide!

Once you’ve finished, you can move to step 4.

Language Discovery

Look at the words in blue in the text in step 1. What do they have in common?

  1.  They all used must and have to.
  2.  These modals all express obligation.

General Notions

Must and have to are both used for obligation and are often quite similar.

must and mustn’t

must/mustn’t + infinitive

  1. You must do your homework assignment

Must I go to the shops now?

  1. You mustn’t leave your shoes lying around 

You mustn’t forget to call your parents tonight

  1. He must throw the rubbish away before he leaves the house
  • Use must to talk about rules and obligations.
  • We use mustn’t to say that something is prohibited.
  • Must and mustn’t are the same for all persons.

have to

have to + infinitive

1. I have to speak Spanish at work.
has to get up early everyday

2. Do I have to buy a uniform for school?
We don’t have to watch this movie
doesn’t have to take the exam

  • We use have to  + verb (infinitive) to talk about rules and obligations. (Use has to for subjects he, she and it)
  • We use don’t have to + verb (infinitive) to say that there is no obligation, or that something is not necessary.

Dig a Little Deeper

must and have to

We use must and have to to talk about rules and obligation. What’s the difference?

  • We usually use have to for an external obligation (a rule at work, at school or a law). 

We have to start school at 8.

  • We normally use must for a personal obligation (one that the speaker imposes to themselves or to others) 

You must go to bed now!

I must finish this today because I won’t have time tomorrow!

mustn’t and don’t have to

Mustn’t and don’t have to are completely different. What’s the difference?

  • You mustn’t wear a tie for the party. (It’s a rule. You can’t come to the party wearing a tie.)
  • You don’t have to wear a tie for the party. (It’s your choice; it’s not necessary, but you can do it)


Ready? Terrific! Let’s move on to step 3 to practise what you’ve learnt in this step.