Joy English
Joy English

B1 Grammar

B1Modal verbs15 min

Obligation and advice: must, have to, should

Say what is necessary, what is not necessary, what is not allowed and what is a good idea.

Must, have to and should all come before the base form of a verb. They show how strong an obligation or a piece of advice is. After must and should, we never use to.

FormMeaningExample
muststrong obligation, often the speaker's own feeling, or a written ruleI must call my mum tonight. It's her birthday.
have to / has toobligation from outside: rules, laws, timetables, jobsNurses have to work at night sometimes.
mustn'tit is not allowed, so don't do itYou mustn't use your phone during the exam.
don't have toit isn't necessary, but you can if you wantYou don't have to bring food. Lunch is included.
should / shouldn'tadvice: a good or bad ideaYou should try the soup. It's delicious.

Must has no past or future form, so we use have to for other times: I had to wait for an hour yesterday. We'll have to leave early tomorrow. Questions and negatives with have to need do, does or did: Do you have to wear a uniform?

Mustn't or don't have to?

These two look similar, but their meanings are very different. Mustn't means something is not allowed. Don't have to means there is no obligation: you can choose.

  • You mustn't swim here. The water is dangerous.
  • You don't have to swim if you're tired. You can sit on the beach.
  • Aiko has to get up at 5 a.m. because her shift starts at six.
  • You should drink more water when it's hot.
  • We didn't have to pay for the concert. It was free.

Exercise 1 of 2

Choose the best form

Choose the option that best completes each sentence.

  1. You _____ touch the paintings. It's against the museum rules.

  2. It's Saturday tomorrow, so I _____ get up early.

  3. You look tired. You _____ go to bed earlier.

  4. Yesterday Kofi _____ work late because his colleague was ill.

  5. _____ you have to wear a uniform at your school?

  6. Visitors _____ show their ticket at the entrance. That's the rule.

  7. You _____ eat so much sugar. It's bad for your teeth.

  8. Lena _____ take the bus to work. She lives very close to her office.

0 of 8 answered

Exercise 2 of 2

Write the correct form

Type the correct form of the words in brackets.

  1. My sister is a doctor, so she (have to) work at weekends sometimes.

  2. We (not / have to) wait long at the airport last night. Our bags came quickly.

  3. You (must / not) tell anyone. It's a secret!

  4. You (should / not) leave your bike outside. Someone might take it.

  5. Students (not / have to) buy the books. The school gives them for free.

  6. (do) Ravi have to work tomorrow?

  7. When I was a child, I (have to) share a bedroom with my two brothers.

  8. Next year, Mina (will / have to) take the bus because her school is moving.

0 of 8 answered

Source

Original lesson by Joy English.

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