Must or Have To?
Must and have to both mean "it is necessary". In most sentences you can use either one. Have to is more common when you speak.
MUST
I must go now.
HAVE TO
I have to go now.
Same meaning.
The big difference is in the negative: mustn't = don't do it · don't have to = you don't need to.
The forms
MUST
SmustV
You must wear a helmet.
No to after it.
MUSTN'T
Smustn'tV
Children mustn't play near the road.
It is not allowed.
HAVE TO
Shave / has toV
She has to work on Saturdays.
Has to for he, she and it.
NEGATIVE · QUESTION
Sdon't / doesn'thave to· Do youhave to…?
He doesn't have to cook tonight. Do you have to wear a tie?
After doesn't, it is still have to.
PAST
Shad toV
We had to wait for an hour.
Must has no past form.
HAVE TO CHANGES, MUST DOES NOT
- she + have toshe has to
- past + have tohad to
- she + mustshe must
- past + musthad to
No musts, no must to, no musted.
TRY IT
- Question 1
"My brother must blank his homework first."
- Question 2
"We missed the last train. We blank take a taxi."
When to use each one
Signs and written rules
Visitors must wear a helmet.
Notices often use must.
Telling someone about a rule
At my school, we have to wear a uniform.
In your own words.
Reminding yourself
I must call Mum tonight.
Nobody is making you.
Mustn't or Don't Have To?
| MUSTN'T · NOT ALLOWED | DON'T HAVE TO · NOT NECESSARY | |
|---|---|---|
| In a test | You mustn't talk during the test. | You don't have to answer every question. |
| At work | You mustn't be late for meetings. | You don't have to wear a suit on Fridays. |
| Medicine | You mustn't take more than two tablets a day. | You don't have to take them with food. |
In everyday speech, people often say can't for "not allowed": You can't park here.
TRY IT
- Question 1
"This is a secret. You blank tell anyone."
- Question 2
"Ngọc has a car, so she blank take the bus."
Common mistakes
Incorrect:Children under six mustn't pay for the bus.
Correct:Children under six don't have to pay for the bus.
They don't need to pay. Mustn't means it's not allowed.
Incorrect:He must to leave now.
Correct:He must leave now.
No to after must.
Incorrect:She musts finish the report.
Correct:She must finish the report.
Must never changes. No -s, even with she.
Incorrect:Last week we must stay at home.
Correct:Last week we had to stay at home.
Must has no past form. Use had to.
Incorrect:Do I must bring my passport?
Correct:Do I have to bring my passport?
Do goes with have to, never with must.
Quick check · 5 questions
Choose the correct form:
Visitors must take off their shoes at the door.
- A. take off — Correct
- B. to take off
- C. taking off
Answer: A. take off
No to after must, and no -ing.
Choose the correct form:
Linh has to take the bus to school.
- A. has to — Correct
- B. have to
- C. must to
Answer: A. has to
He, she and it use has to.
Choose the correct words:
You mustn't swim here. The water is too deep.
- A. mustn't — Correct
- B. don't have to
Answer: A. mustn't
Don't have to = not necessary.
Choose the correct words:
Tomorrow is a holiday, so the children don't have to go to school.
- A. don't have to — Correct
- B. mustn't
- C. doesn't have to
Answer: A. don't have to
The children = they: don't, not doesn't.
Choose the word that starts the question:
Do you have to work this weekend?
- A. Do — Correct
- B. Must
- C. Are
Answer: A. Do
Are does not go with have to.
See whether it really stuck.
Start the quiz · 14 questions
