B1 Modals of obligation
Must, have to, and should are modal verbs we use to talk about rules, obligations, advice, and prohibition in English.
- Must = strong obligation: You must wear a seatbelt when you drive.
Must is more formal, and we often use it for personal opinions about ourselves: I’m overweight! I must go on a diet.
- Have to = external rule or necessity (We have no choice): I have to work tomorrow.
Have to is more informal, and we often use it for rules from work, government, parents that we cannot influence: Everyone has to pay tax.
Should is used for advice or recommendations: You should go and see „Star War 5”. It’s great!
Mustn’t is used for prohibition (The things we are not allowed to do): You mustn’t smoke in the hotel.
Don’t have to is used when there is no obligation: You don’t have to pay to go in the museum.
Don’t have to also shows we can choose what we want to do: You don’t have to come to my party if you’re tired.(But I would like you to!)
These verbs are extremely important and common in spoken and written English, especially when talking about school, work, laws (from the government), health, travel, and daily responsibilities.
Zdania twierdzące
MUST
Positive: Subject + must + (always infinitive) verb
- I must get up now or I’ll be late!
Past: THERE IS NO PAST FORM OF „MUST” (USE „HAD TO”)
Negative: Subject + mustn’t + (always infinitive) verb
- You mustn’t drive too fast.
Questions
Must + subject + (always infinitive) verb?
- Must I pay everything now?
Questions with must are possible but very unusual in everyday English conversations. Native speakers prefer have to. (Do I have to finish the project today?)
HAVE TO
Positive
Subject + have/has to + verb
- I have to work late.
- Julie has to wear a uniform at work.
Past
Subject + had to + verb
- We had to wait two hours for our food.
Negative
Subject + don’t/doesn’t have to + verb
- You don’t have to pay everything now. (You can pay some now, and some later)
- He doesn’t have to come tomorrow. (We don’t need him)
Questions
Do/Does + subject + have to + verb?
- Do you have to wear a suit at work?
- Does she have to pay for the first meeting?
SHOULD
Positive
Subject + should + verb
- Your eyes look dark. You should sleep more.
Negative
Subject + shouldn’t + verb
- You shouldn’t eat so much junk food. It’s bad for you!
- Sam shouldn’t drive so fast. He’ll have an accident.
Questions
Should + subject + verb?
- What do you think? Should I tell her about the new boss?
- Should we book tickets now or later?
When We Use “MUST”
MUST is used for: Strong Obligation / Rules / Personal Authority
We use must when:
- you feel something is very important: It’s your son’s birthday party. You mustn’t be late.
- giving strong instructions (formal): (sms from Ryanair) „Passengers must check in two hours before take off.”
- talking about laws or official rules: (email from the government) „Tax must be paid by the 10th of the month.”
Common situations
- (road) signs and notices
- formal instructions
- strong spoken emphasis
Examples
- You must wear protective glasses.
- Passengers must show identification.
- You must wait here until the doctor is ready.
Formal or informal?
- Formal – More formal than have to
- „Must” is common (usual) in written rules and notices (road signs, regulations, laws)
- „Must” sounds very strong and formal in spoken English
When We Use “MUSTN’T”
MUSTN’T is used when something is prohibited, illegal, or not allowed.
Examples
- You mustn’t smoke in the office.
- Visitors mustn’t enter this area.
- You mustn’t use your phone in the exam.
Important! Mustn’t does NOT mean “not necessary”.
You mustn’t come tomorrow. (IT IS FORBIDDEN. DO. NOT. COME.)
You don’t have to come tomorrow. (IT IS YOUR CHOICE)
When We Use “HAVE TO”
Have to is used for: rules, schedules, laws (EXTERNAL RULES – Given by other people (parents, your boss, the government, religion etc).
Examples
- I have to pay my electricity bill tomorrow. (Tauron will cut me off if I don’t)
- Julie has to wear a uniform at work. (The company’s rules)
- We have to arrive at the train station before 8 p.m. (The train will leave!)
Formal or informal?
- Informal – It is very common in everyday „normal” spoken English
- It sounds more natural than must in conversation
When We Use “DON’T HAVE TO„
DON’T HAVE TO is used when something is optional (We can choose).
Examples
- We don’t have to vote in elections. (We choose!)
- Retired people don’t have to work. (They choose!)
- In a restaurant, you don’t have to eat all your food. (You choose!)
When We Use “SHOULD”
SHOULD is used for: Advice and recommendations.
We use should to:
- give advice: If you want to lose weight, I think you should eat more vegetables.
- suggest good ideas: We should go to Spain on holiday!
- express opinions: Jim is so lazy. I think he should be fired!
Formal or informal?
- „Should” is very popular in both spoken and written English – We use it a lot 🙂
Common Mistakes
She should to study more. ❌ „She should study more.” We never use „TO” after a modal verb.
