Lesson 34 · Stage 3: Plans, requests & comparing
Obligation: must / have to / need to
BeginnerForm & use
saying that something is necessary
1.Form
Three ways to say something is necessary: must, have to, need to — all + base form. Must is a modal verb; have to and need to work like ordinary verbs.
| must | have to | need to | |
|---|---|---|---|
| Affirmative | I / she must go. | I have to go. · She has to go. | I need to go. · She needs to go. |
| Negative | mustn't go (= don't do it) | don't / doesn't have to go (= not necessary) | don't / doesn't need to go (= not necessary) |
| Question | Must I go? (rare) | Do I have to go? · Does she have to go? | Do I need to go? |
| Past | — (use had to) | had to go | needed to go |
Must never takes -s, to or do: She must go. Have to / need to are the opposite: She has to go. Does she need to go?
2.When to use them
1. have to — necessary because of rules, work or circumstances (a fact, not the speaker's opinion)
I have to wear a uniform at work.
Linh has to take two buses to get to school.
Do you have to work on Sundays?
2. must — the speaker personally feels it is necessary: a reminder to yourself, or a strong recommendation
It's late. I must go.
I must call my grandma this weekend.
You must try the coconut coffee here — it's amazing!
3. must — written rules, signs and instructions
All visitors must sign in at the front desk.
Passengers must keep their bags with them at all times.
4. need to — something is necessary for a purpose or because of the situation
My phone is almost dead. I need to charge it.
Do we need to book a table, or can we just walk in?
5. have got to — the same as have to, very common in informal speech
Sorry, I've got to go — my bus is leaving.
In American English, must for obligation sounds quite strong and formal; Americans usually say have to or have got to (gotta). If in doubt, have to is almost always fine.
3.Other tenses: use have to
Must has only one form and only talks about the present or future. For the past, after will / might, in the present perfect or after another verb, use have to.
| Time / form | Example |
|---|---|
| Past | I had to wait an hour for the bus. |
| Future | Prices go up next month, so we'll have to pay more. |
| Might have to | We might have to sell the car. |
| Present perfect | I've had to wear glasses since I was ten. |
| After another verb | I hate having to get up in the dark. |
4.Mustn't is very different from don't have to
| Meaning | Example | |
|---|---|---|
| mustn't | don't do it — it's not allowed | You mustn't smoke in here. It's a hospital. |
| don't have to / don't need to | it isn't necessary — you can if you want | You don't have to bring food. There's plenty. |
You mustn't touch the paintings.
You don't have to take your shoes off. Come in!
mustn't = it's forbidden; don't have to = it's optional. Don't mix them up. See also the lesson “No obligation: don't have to / needn't”.
5.Common mistakes
You must to turn off your phone in class.You must turn off your phone in class.
No to after must.
She have to finish her homework.She has to finish her homework.
he/she/it → has to.
Last week I must work every evening.Last week I had to work every evening.
For the past, use had to.
Do you must wear a helmet?Do you have to wear a helmet?
Don't use do with must; ask Do you have to…?
We will must show our passports.We will have to show our passports.
Future: will have to.
She needs wear a uniform.She needs to wear a uniform.
need as an ordinary verb → need to + verb.
Examples
- All students must wear a uniform at this school.
- My brother has to work on Saturdays.
- Did you have to pay for the tickets?
- Yesterday I had to stay late at the office to finish a report.
