B2 · Intermedio alto Capítulo 18

Modal Verbs: Permission, Obligation, Prohibition and Necessity

4 Reglas totales
20 ejemplos
1 min
Reglas en este capítulo Práctica rápida

Chapter in 30 Seconds

Master the nuances of modal verbs to express rules, requirements, and permissions with total confidence.

  • Distinguish between internal and external obligations.
  • Navigate the subtle differences between prohibition and absence of necessity.
  • Express formal and informal permissions using standard and alternative phrases.
Command the rules of English with precision.

Lo que aprenderás

A complete B2 guide to modal verbs for permission, obligation, prohibition and necessity: must, have to, mustn't, needn't, may, be allowed to, be supposed to, and all their nuanced distinctions.

Learning Objectives

By the end of this chapter, you will be able to:

  1. 1
    By the end you will be able to: Differentiate between internal and external obligation using must and have to.
  2. 2
    By the end you will be able to: Distinguish between prohibition and lack of necessity in professional contexts.

Consejos y trucos (4)

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The 'Must' Trap

Avoid using 'must' in questions. It sounds like you are demanding an answer. Use 'Do I have to' instead.
frontend.learn_grammar.from_rule: Obligation and Necessity: Must, Have To, Need To
💡

Context is King

Always ask yourself: Is this a rule or a choice?
frontend.learn_grammar.from_rule: Prohibition vs. No Necessity: Mustn't vs. Don't Have To
💡

Use 'May' for respect

When in doubt in a professional setting, use 'may'.
frontend.learn_grammar.from_rule: Permission: Can, May, Be Allowed To, Be Supposed To
💡

The 'Needn't Have' Trap

Always use 'needn't have' for past mistakes. It shows you know the action was completed.
frontend.learn_grammar.from_rule: Needn't, Don't Need To, Didn't Need To, Needn't Have: No Obligation

Vocabulario clave (5)

Mandatory Required by rule or law Optional Not required Forbidden Not allowed Authority Power to enforce rules Discretion Freedom to decide

Real-World Preview

briefcase

Office Protocol

Review Summary

  • Must/Have to + base verb
  • Mustn't + base verb
  • Be allowed to/May
  • Needn't/Don't need to

Errores comunes

Must is not used in the negative for obligation; use 'don't have to' instead.

Wrong: I don't must go.
Correcto: I don't have to go.

Mustn't means it is forbidden, not that it is optional.

Wrong: You mustn't pay if you don't want to.
Correcto: You don't have to pay if you don't want to.

Modals do not take the third-person 's' and are followed by the bare infinitive.

Wrong: He musts to work.
Correcto: He must work.

Next Steps

You have done an amazing job today! Keep practicing these nuances, and you will sound increasingly natural.

Listen to a news report and note the modal verbs used to describe laws.

Continue to: Get: Different Meanings and Uses

Práctica rápida (10)

Find the error.

Find and fix the mistake:

She mustn't to clean the house.

✓ Correct! ✗ Not quite. Correct answer: to
Mustn't is followed by base verb.

frontend.learn_grammar.from_rule: Prohibition vs. No Necessity: Mustn't vs. Don't Have To

Fill in the blank with the correct form.

You ___ wear a seatbelt by law.

✓ Correct! ✗ Not quite. Correct answer: have to
It is an external rule.

frontend.learn_grammar.from_rule: Obligation and Necessity: Must, Have To, Need To

Fix the error.

Find and fix the mistake:

You don't must smoke here.

✓ Correct! ✗ Not quite. Correct answer: You mustn't smoke here.
Prohibition requires mustn't.

frontend.learn_grammar.from_rule: Obligation and Necessity: Must, Have To, Need To

Choose the correct modal.

You ___ pay for the entry; it's free.

✓ Correct! ✗ Not quite. Correct answer: don't have to
It is not necessary.

frontend.learn_grammar.from_rule: Prohibition vs. No Necessity: Mustn't vs. Don't Have To

Fill in the blank with mustn't or don't have to.

You ___ smoke in the hospital.

✓ Correct! ✗ Not quite. Correct answer: mustn't
It is a rule.

frontend.learn_grammar.from_rule: Prohibition vs. No Necessity: Mustn't vs. Don't Have To

Fill in the blank.

You ___ finish the work today; tomorrow is fine.

✓ Correct! ✗ Not quite. Correct answer: don't have to
It is optional.

frontend.learn_grammar.from_rule: Prohibition vs. No Necessity: Mustn't vs. Don't Have To

Choose the correct sentence.

Which sentence is correct?

✓ Correct! ✗ Not quite. Correct answer: I must go.
Must is a modal verb.

frontend.learn_grammar.from_rule: Obligation and Necessity: Must, Have To, Need To

Choose the correct form.

We ___ to smoke here.

✓ Correct! ✗ Not quite. Correct answer: are not allowed
Need 'to be' and past participle.

frontend.learn_grammar.from_rule: Permission: Can, May, Be Allowed To, Be Supposed To

Fill in the blank.

I ___ to be at the meeting at 9.

✓ Correct! ✗ Not quite. Correct answer: am supposed
Supposed to means expected.

frontend.learn_grammar.from_rule: Permission: Can, May, Be Allowed To, Be Supposed To

Choose the best fit.

___ I ask a question?

✓ Correct! ✗ Not quite. Correct answer: May
May is polite.

frontend.learn_grammar.from_rule: Permission: Can, May, Be Allowed To, Be Supposed To

Score: /10

Preguntas frecuentes (6)

No, 'must' has no past form. Use 'had to' instead.
Yes, it is often used in formal writing or by authority figures.
No, 'mustn't' is not used in questions. Use 'do I have to' instead.
Yes, it is often used in official rules and signs.
It's better to use 'may' or 'could'. 'Can' might sound too casual.
Modals like 'can' are followed by the base verb without 'to'.
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Formal Connectors and Discourse Markers
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