Lesson 19: Modal Verbs

Can · Could · Must · Have to · Should · Shall · May · Be able to
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Modal Verbs & Context Vocabulary

Click 🔊 to hear each word. Click 🔊 to hear each word.
The Modal Verbs
can/kæn/ability / permission (present)
can't / cannot/kɑːnt/inability / no permission
could/kʊd/past ability / polite request
couldn't/ˈkʊdnt/could not
must/mʌst/strong personal obligation
mustn't/ˈmʌsnt/PROHIBITION — do not do it!
have to/ˈhæv tə/external obligation (rules)
don't have to/dəʊnt ˈhæv tə/not necessary — optional
should/ʃʊd/advice — a good idea
shouldn't/ˈʃʊdnt/negative advice — a bad idea
shall/ʃæl/offer / suggestion (I / We)
may/meɪ/formal permission
be able to/biː ˈeɪbl tə/formal ability / other tenses
Work & Rules
rule/ruːl/rule
law/lɔː/law
permission/pəˈmɪʃn/permission
sign/saɪn/notice / sign
uniform/ˈjuːnɪfɔːm/uniform
deadline/ˈdedlaɪn/deadline
appointment/əˈpɔɪntmənt/meeting / appointment
emergency/ɪˈmɜːdʒənsi/emergency
passport/ˈpɑːspɔːt/passport
ticket/ˈtɪkɪt/ticket
Common Actions with Modals
drive/draɪv/to drive
swim/swɪm/to swim
smoke/sməʊk/to smoke
vote/vəʊt/to vote
park/pɑːk/to park
enter/ˈentər/to enter
rest/rest/to rest
take medicine/teɪk ˈmedsɪn/to take medicine

Grammar Lab

A · The Three Golden Rules

These rules apply to CAN, COULD, MUST, SHOULD, SHALL, MAY

NO -s
No 3rd person -s
He cans swim.
She musts go.
✔ He can swim.
✔ She must go.
The verb stays the same for ALL persons
NO to
No infinitive marker
I must to go.
You should to rest.
✔ I must go.
✔ You should rest.
⚠️ Exception: have to keeps "to"
NO do/does
No auxiliary for questions/negatives
Do you can help?
Does she must go?
✔ Can you help?
✔ Must she go?
⚠️ Exception: have to uses do/does

⚠️ The "have to" exception — both "to" AND do/does

Have to is not a "true" modal — it behaves like a regular verb for questions and negatives:

  • ✔ Do you have to wear a uniform?  (not "Have you to…")
  • ✔ She doesn't have to come.  (not "She hasn't to come")
  • ✔ Does he have to pay?  (3rd person uses does and has to)
Exercise A  Easy  — Which sentence is correct?
1.
2.
3.
4.
5.
Exercise B  Hard  — Correct the mistake
1. "He cans speak French." → Correct:
2. "You should to rest." → Correct:
3. "Do you can help me?" → Correct:
4. "She musts study." → Correct:
CAN

Ability and Permission (Present)

Affirmative (+)Negative (−)Question (?)Short Answer
I can swim.I can't swim.Can I swim?Yes, I can.
You can swim.You can't swim.Can you swim?No, you can't.
He / She can swim.He / She can't swim.Can he swim?Yes, he can.
We / They can swim.We / They can't swim.Can they swim?No, they can't.

🎯 Two uses of CAN

  • Ability: "I can cook." / "She can't drive yet."
  • Permission: "You can park here." / "You can't smoke here."
Exercise C  Easy  — Choose the correct form
1. She ___ drive — she passed her test last week.
2. ___ I use your pen, please?
3. They ___ park here — it is a bus stop.
4. ___ he speak Bulgarian?
COULD

Past Ability and Polite Requests

Past Ability

I could run fast as a child.
She could read at age 4.
We couldn't swim back then.
Could you drive at 18?
Polite Request (more formal than Can)

Could you help me, please?
Could I have the menu?
Could you speak more slowly?
Exercise D  Easy  — Past ability or polite request?
1. "Could you pass the salt?" →
2. "She could swim at age 3." →
3. "Could I use the bathroom?" →
4. "I couldn't speak English five years ago." →
5. "Could you explain that again?" →
6. "He couldn't drive when he was 15." →
MUST

Strong personal obligation — YOU feel it is important

Affirmative (+)Negative — MUSTN'T (Prohibition!)Question
I must call her.I mustn't forget.Must I go?
You must stop.You mustn't smoke here.Must you shout?
He / She must pay.He mustn't enter.Must she come?
We / They must leave.They mustn't be late.Must they stay?

🎯 When to use MUST (not Have to)

  • The feeling comes from you personally — it is your own judgment or priority.
  • "I must call my mother."  (I feel it is important to me)
  • "You must try this restaurant!"  (strong personal recommendation)
  • "I must finish this today."  (self-imposed deadline)
HAVE TO

External obligation — a rule, a law, or someone else requires it

Affirmative (+)Negative (−)Question (?)
I / You / We / TheyI have to wear a uniform.I don't have to work late.Do you have to go?
He / She / ItShe has to study.She doesn't have to come.Does he have to pay?

⚠️ 3rd person: have to → HAS to

Unlike true modals, have to changes in the 3rd person singular — just like a regular verb.

  • I/You/We/They have to go.  →  He/She/It has to go.
  • Do you have to work?  →  Does she have to work?
  • ❌ "She have to go."   ✔ "She has to go."

🎯 When to use HAVE TO (not Must)

  • The rule comes from outside you — the law, your boss, a sign, an institution.
  • "I have to wear a uniform."  (the company requires it)
  • "You have to show your passport."  (airport/hotel rule)
  • "She has to pay taxes."  (the law)
Exercise E  Easy  — Must or Have to?
1. "I ___ call my mum — it's her birthday."
2. "I ___ show my passport at the border."
3. "She ___ finish the report — her boss said so."
4. "You ___ try this coffee — it's amazing!"
5. "Drivers ___ stop at a red light."
MUSTN'T vs DON'T HAVE TO

Same translation in Bulgarian — completely different meaning in English

MUSTN'T 🚫
Prohibition — Do not do it! It is dangerous or illegal.
"You mustn't smoke here."
(It is forbidden. There is a No Smoking sign.)

"You mustn't drive through a red light."
(Illegal. It is dangerous.)

"You mustn't open that door."
(Don't do it — it is forbidden.)
DON'T HAVE TO ✅
No obligation — you can do it if you want, but it is not necessary.
"You don't have to wear a tie."
(It is not required — but you can if you want.)

"She doesn't have to come on Saturday."
(It is not necessary — her choice.)

"I don't have to cook tonight — there is food."
(No obligation. I can relax.)

⚠️ The classic Bulgarian mistake

  • In many languages both translate the same way — but in English the meaning is completely different.
  • Mustn't = STOP. It is a prohibition. Doing it is wrong or dangerous.
  • Don't have to = FREE CHOICE. You may do it if you want — there is just no obligation.
  • Memory trick: mustn't = must not = never do it  |  don't have to = no need = optional
Exercise F  Easy  — Mustn't or Don't have to?
1. "It's Sunday — you ___ wake up early."
2. "This is a library — you ___ make noise."
3. "The ticket is free — you ___ pay."
4. "Danger! You ___ touch that wire."
5. "The meeting is optional — she ___ come."
6. "No Entry sign — you ___ go in there."
Exercise G  Hard  — Fill in: mustn't / must / don't have to / doesn't have to
1. The entrance is free. You ___ buy a ticket.
2. This is a hospital. You ___ smoke inside.
3. She works from home. She ___ commute.
4. I ___ finish this report — the deadline is today!
SHOULD / SHOULDN'T

Advice (positive) / Negative Advice

SHOULD (+) — positive advice

You should sleep more.
He should see a doctor.
We should leave early.
Should I take an umbrella?
SHOULDN'T (−) — negative advice

You shouldn't eat so much sugar.
She shouldn't work so late.
They shouldn't smoke.

💡 Should vs Must — how strong is the obligation?

  • Should = advice / opinion. It would be a good idea. You can choose.
  • Must = strong obligation. It is important / required. You need to do it.
  • "You should eat breakfast."  (advice — it is good for you)
  • "You must pay your taxes."  (obligation — the law requires it)
Exercise H  Easy  — Should or Shouldn't?
1. You look tired — you ___ get more sleep.
2. You ___ drink coffee at midnight — you won't sleep.
3. She has a headache — she ___ take a painkiller.
4. The weather is cold — you ___ wear a coat.
5. You ___ eat before swimming — it can make you feel sick.
6. You have an exam tomorrow — you ___ study tonight.
SHALL

Offering to do something / Suggesting doing something together

Shall I … ? — Offering to do something

Shall I open the window?
Shall I carry that for you?
Shall I call a taxi?
= Do you want me to …?
Shall we … ? — Suggesting doing together

Shall we go?
Shall we have lunch?
Shall we dance?
= What do you think about us doing …?

💡 Shall is mostly used with I and We

At A1 level you will almost always see Shall I … and Shall we …. It is not commonly used with you/he/she/they in modern English.

Exercise I  Easy  — Offer or Suggestion?
1. "Shall I make some coffee?" →
2. "Shall we watch a film tonight?" →
3. "Shall I help you with that bag?" →
4. "Shall we start the meeting?" →
5. "Shall I call a taxi for you?" →
6. "Shall we go for a walk?" →
MAY

Formal way to ask for permission — more polite than Can

🎯 When to use May

  • Asking for permission formally: "May I come in?" / "May I use the bathroom?"
  • Giving permission formally: "You may sit down." / "Students may leave at 3pm."
  • Used especially in: schools, offices, formal situations, shops, doctors' offices.
Informal
Can
"Can I use your phone?"
"Can I sit here?"
Polite
Could
"Could I use your phone?"
"Could I sit here?"
Formal
May
"May I use your phone?"
"May I sit here?"
Exercise J  Easy  — Can or May?
1. You are in a job interview. You need to use the bathroom. →
2. You are chatting with your best friend. →
3. "You ___ leave when you finish the test."
4. You see a jacket you like on the shelf. You say: "___ I see that jacket?"
BE ABLE TO

Formal ability — and the only way to express ability in other tenses

💡 Why use "be able to" instead of "can"?

  • Can has no infinitive or past participle form — be able to fills those gaps.
  • After other modals: "You will be able to drive soon." (not "will can")
  • In formal/written English: "I am able to attend the meeting on Friday."
  • Past: "I was able to finish the project." (specific achievement — different from could)
TenseFormExample
Presentam / is / are able to"She is able to start immediately."
Pastwas / were able to"They were able to fix it."
Futurewill be able to"You will be able to drive next year."
Quick Reference — All Modals

One table — all modals

ModalUseMeaning in contextExample
canability / permission (present)ability / permission"I can swim."
can'tinability / no permissioninability / no permission"You can't park here."
couldpast ability / polite requestpast ability / polite request"Could you help?"
muststrong personal obligationstrong personal obligation"I must call her."
mustn'tPROHIBITION 🚫PROHIBITION 🚫"You mustn't smoke here."
have toexternal obligationexternal obligation"I have to wear uniform."
don't have tono obligation (optional) ✅not necessary — optional ✅"You don't have to come."
shouldadviceadvice"You should rest."
shouldn'tnegative advicenegative advice"You shouldn't eat that."
shalloffer / suggestion (I/we)offer / suggestion"Shall I help?"
mayformal permissionformal permission"May I come in?"
be able toformal ability / other tensesformal / other tenses"She will be able to drive."

Reading Texts

Read each text carefully, then answer the three questions.
Text 1 of 2

The New Job

Teodor starts a new job at a software company on Monday. Before his first day, his manager sends him an email with the company rules.

Teodor has to arrive by 9am every day. He doesn't have to wear a uniform, but he must look professional. He must not use his phone during meetings. He can eat lunch at his desk or in the kitchen — it is his choice.

His manager also gives him some advice. She says he should introduce himself to the team on the first day. He shouldn't be shy — the team is very friendly. He could also ask his colleague Marta for help, because she has worked there for five years and knows everything.

"May I work from home sometimes?" Teodor asks in his reply. "Yes, you may work from home on Fridays," says his manager. "But you have to be online by 9am on those days too."

1. Which rule is a PROHIBITION (mustn't / must not)?
2. What does "He doesn't have to wear a uniform" mean?
3. When can Teodor work from home?
Text 2 of 2

At the Doctor

Maria has a bad cough and goes to see her doctor, Dr Petrov. She waits in the waiting room and then a nurse opens the door: "May I call you in now, Maria?"

Dr Petrov examines her and gives her advice. "You should rest at home for two or three days," he says. "You mustn't go to work — you could make your colleagues sick too. You must take this medicine three times a day. You can eat normally, but you shouldn't drink cold drinks."

Maria asks: "Do I have to stay in bed all day?" Dr Petrov shakes his head. "No, you don't have to stay in bed. You can sit on the sofa and watch television. But you should drink a lot of warm water and tea."

"Can I go outside?" asks Maria. "You can go outside for a short walk, but you mustn't go to crowded places," says Dr Petrov. "Could you come back in five days?" he adds. "Yes, I can," says Maria.

1. Why mustn't Maria go to work?
2. Does Maria have to stay in bed all day?
3. What is the doctor's instruction about going outside?

Grammar Exercises — 18 Sets

Scroll down to practise all modal verbs.