MUST

Modal verb MUST

1. Use MUST to express necessity or obligation based on a rule, a law, or an instruction

The passengers must remain seated until the plane has landed.

People must drive carefully and wear a seatbelt at all times.

Doctors must do what’s best for the patient.

2.   Use MUST to express the regulation

Candidates must meet several requirements to be allowed to compete.

Payment must be done before receiving the service.

3. Use MUST to express deduction – sure that something is true (certainty)

We use this when we don't know but we are certain that it is true (based on evidence)

The ground was wet this morning. It must have rained last night.

You look exhausted this morning! You must have studied all night.

You must be our new teacher.

4.   Use MUST to express positive logical assumption (must + have + past participle)

You must have been very hungry to eat the pizza so quickly.

Her car is outside, so she must have come back yesterday.

5. Use MUST to express a strong recommendation

You must try this cake, it’s fantastic.

You must come eat lunch with us.

The ice cream here is delicious. You must try some.

6. Use MUST to express annoyance or irritation (in questions)

Must you always say this?

Why must he always interrupt?

Mustn’t

1. Use MUSTN’T to express prohibition

You mustn't use your phone while you are driving.

She mustn’t smoke in the restaurant.

People must not drive under the influence of alcohol.

We must not tell anyone.

MUST vs. HAVE TO

Similarities:

1.  MUST and HAVE TO both express necessities. 

All students must take the exam to receive a diploma.

All students have to take the exam to receive diploma.

2. In everyday statements of necessity HAVE TO is used more commonly than MUST

Although MUST can be replaced with HAVE TO in some sentences, there are some differences between them:

1. MUST is usually stronger than HAVE TO and indicates urgency or emphasizes importance

I have to talk to my sister about her wedding.

I must speak with my sister right now, it’s urgent.

2. MUST expresses obligation imposed by the speaker while HAVE TO expresses external obligation.

Teacher: You must complete this project till Monday.

Student: We have to complete this project till Monday.

3. When we speak about someone else's obligations, we use HAVE TO.

Tom has to quit smoking.

4.  For questions it is more common to use HAVE TO instead of MUST (which sounds very formal):

When do you have to finish the project?

Why do we have to remain seated in the plane?

5. The past tense of MUST is HAD TO

I had to visit my dentist yesterday, but I forgot.

MUSTN’T vs. DON’T HAVE TO

When used in the negative, MUST and HAVE TO have different meanings.

MUSTN’T = prohibition = negative obligation

DO NOT HAVE TO = lack of necessity

You mustn’t tell anyone, it’s a secret.

I mustn’t forget to take my keys.

She mustn’t be rude to the customers.

You do not have to go to school tomorrow, it’s a holiday.

I don’t have to go to the doctor, I’m feeling much better.

She doesn’t have to invite me to her party if she doesn’t want me to be there.

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Модални глаголи 😃 Modal verbs

CAN - COULD
MAY - MIGHT
WILL
WOULD
SHALL
SHOULD
MUST
DARE
OUGHT TO
HAD BETTER
NEED
BE ABLE TO