Modal verbs are small words with big power. They help us express possibility, necessity, advice, permission, and ability—all essential parts of everyday interaction. In this unit, we’ll explore modal verbs like can, must, should, may, might, have to, and would, and learn how they change the tone and meaning of a sentence.
You’ll practice asking for permission (Can I…?), giving advice (You should…), and expressing obligation (You have to…). We’ll also look at how modals are used to soften language in polite requests or to make suggestions. This unit focuses not only on grammar but also on communicative function, helping you sound more natural, respectful, and confident in common situations.

13.1 INTRODUCTION TO MODAL VERBS (CAN, MUST, SHOULD, HAVE TO)
Objective:
To introduce the most common modal verbs in English—can, must, should, and have to—and explain their use in expressing ability, necessity, obligation, and advice.

🔹 WHAT ARE MODAL VERBS?
Modal verbs are auxiliary verbs that modify the meaning of the main verb. They express things like:
Ability → can
Obligation → must, have to
Advice → should
Permission → can, may (formal)
Possibility → might, could
✅ Modal verbs are always followed by the base form of the main verb:
She can swim. ❌ She can to swim.

🔸 KEY MODALS INTRODUCED IN THIS LESSON
Modal    Function    Example
can    ability / permission    I can speak English. / Can I come in?
must    strong obligation    You must wear a seatbelt.
should    advice / recommendation    You should study more.
have to    external obligation    I have to pay my taxes.

🔹 DIFFERENCES IN USE
Must vs. Have to    Explanation
You must stop here.    Speaker feels the rule is important (internal obligation)
You have to stop here.    It's a law or external rule (external obligation)
Should vs. Must    Explanation
You should eat vegetables.    Advice or suggestion
You must eat vegetables.    Strong recommendation / obligation

🔸 MODAL VERB + BASE VERB: STRUCTURE
Subject    Modal + Verb (no “to”)
I    I can swim.
You    You should study.
He / She    He must leave now.
We / They    We have to finish this.
✅ Only “have to” changes with subject (has to / don’t have to):
She has to go. / They don’t have to leave.

🔹 NEGATIVE FORMS
Modal    Negative Form Example
can’t    You can’t park here.
mustn’t    You mustn’t smoke inside. (prohibited)
shouldn’t    You shouldn’t eat so much sugar.
don’t have to    You don’t have to come if you’re busy. (no obligation)
✅ Mustn’t = prohibited
✅ Don’t have to = not necessary, but allowed

🧠 COMMON SENTENCE PATTERNS
Subject + modal + base verb
→ He should exercise more.
Modal (negative) + base verb
→ You mustn’t touch that.
Question with modal
→ Can I ask you a question?
→ Should we start now?

❗ COMMON MISTAKES
Mistake    Correction    Why?
She can to drive.    She can drive.    No “to” after modal
I must to go.    I must go.    Same rule: base verb only
He has to studies.    He has to study.    Main verb stays in base form
You don’t must do it.    You don’t have to do it.    “Must” doesn’t use “do” in negatives

💬 EXAMPLE DIALOG
Tina: Can you drive a manual car?
Leo: Yes, I can. But I have to renew my license soon.
Tina: You should do that before the end of the month.
Leo: I know. They said I must take a new test if I wait too long.

13.2 EXPRESSING ABILITY AND POSSIBILITY
Objective:
To learn how to express ability and possibility using modal verbs, especially can, could, and be able to, in both present and past contexts.

🔹 EXPRESSING ABILITY IN THE PRESENT
Use can to talk about what someone is able to do now.
Subject + can + base verb    Example
I can swim.    I can swim 500 meters without stopping.
She can speak three languages.    She can speak English, Spanish, and French.
We can use this software.    We can use it to edit videos.
✅ Use can with base form of the verb.
✅ No “to”: ❌ She can to run fast → ✔ She can run fast

🔸 EXPRESSING ABILITY IN THE PAST
Use could or was/were able to for past ability.
Form    Use Example
could + base verb    When I was a child, I could climb trees.
was/were able to    She was able to finish the project on time.
couldn’t    He couldn’t understand the instructions.
✅ Could = general past ability
✅ Was able to = specific success in a situation

🔹 FUTURE AND GENERAL ABILITY
Time    Modal Expression    Example
Future    will be able to    You’ll be able to download it tomorrow.
General Possibility    can (sometimes)    You can see whales in this area.
Theoretical Ability    could    It could be dangerous.
✅ Use will be able to for future ability

🔸 EXPRESSING POSSIBILITY
Use can, could, and may/might to talk about what is possible.
Modal    Example
can    Accidents can happen anytime.
could    That could be the answer.
may / might    It may rain later. / She might be at home.
✅ Could / may / might = less certain than can

🧠 SUMMARY TABLE
Function    Present    Past    Future
Ability    can    could / was able to    will be able to
Possibility    can / could / might    could / might    could / might / may

❗ COMMON MISTAKES
Mistake    Correction    Why?
He can to speak Italian.    He can speak Italian.    No “to” after “can”
I could to swim when I was five.    I could swim when I was five.    Same rule
She was able finish it.    She was able to finish it.    Missing “to” after “able”
They can comes later.    They can come later.    Use base verb

💬 EXAMPLE DIALOG
Noah: Can you drive?
Lina: Yes, but I couldn’t until last year. I finally got my license.
Noah: That’s great! I hope I’ll be able to pass the test next month.
Lina: You can do it. Just keep practicing—especially parking!

13.3 GIVING ADVICE AND EXPRESSING OBLIGATION
Objective:
To use modal verbs like should, must, and have to to give advice, express obligation, and distinguish between strong necessity and recommendation.

🔹 GIVING ADVICE: “SHOULD” AND “OUGHT TO”
Use should (and its formal alternative ought to) to suggest what is the right or good thing to do.
Subject + should + base verb    Example
You should rest if you’re tired.    (advice / recommendation)
We should leave earlier tomorrow.    (suggestion)
He shouldn’t skip breakfast.    (negative advice)
You ought to visit that museum.    (formal or written English)
✅ “Should” is very common in spoken English.
✅ “Ought to” is more formal and less frequent.

🔸 EXPRESSING STRONG OBLIGATION: “MUST” VS. “HAVE TO”
Both must and have to express necessity, but they are used slightly differently:
Modal    Example    Context
must    You must wear a helmet.    Strong internal or official rule
have to    I have to get up early tomorrow.    External requirement or routine
has to    She has to finish the report by 5.    Third person singular
✅ “Must” often sounds stronger or more formal than “have to”.

🔹 DIFFERENCES BETWEEN “MUST” AND “SHOULD”
Use “must” when...    Use “should” when...
It’s a law or rule    It’s a good idea, but not required
The speaker insists    The speaker is giving advice
There's a serious consequence    There’s just a suggestion
Examples:
You must stop at the red light. (obligation/law)
You should eat more vegetables. (advice)

🔸 NEGATIVE FORMS
Modal    Negative Form    Meaning
mustn’t    You mustn’t smoke here.    Prohibited
don’t have to    You don’t have to come.    Not necessary (optional)
shouldn’t    You shouldn’t drive so fast.    Bad idea / warning
❗ Mustn’t = not allowed
❗ Don’t have to = not required, but allowed

🧠 SENTENCE PATTERNS
You should + base verb → You should call your parents.
You must / have to + base verb → You must study more.
You don’t have to + base verb → You don’t have to stay late.
You mustn’t + base verb → You mustn’t be late.

❗ COMMON MISTAKES
Mistake    Correction    Why?
You should to go home.    You should go home.    No “to” after modal
She musts arrive soon.    She must arrive soon.    Modal verbs don’t take “-s”
I have study now.    I have to study now.    Use “have to” for obligation
You don’t must pay.    You don’t have to pay.    “Must” doesn’t use “do” in negatives

💬 EXAMPLE DIALOG
Toby: I have a terrible headache.
Lena: You should drink some water and rest.
Toby: I think I have to leave work early.
Lena: You must see a doctor if it doesn’t get better.
Toby: OK. I won’t wait too long. Thanks for the advice.

13.4 MAKING REQUESTS AND ASKING FOR PERMISSION
Objective:
To learn how to use modal verbs like can, could, may, and would to make requests and ask for permission politely and appropriately in different contexts.

🔹 ASKING FOR PERMISSION
Modal    Politeness Level    Example
Can I…?    Neutral/informal    Can I go to the bathroom?
Could I…?    More polite    Could I leave a bit early today?
May I…?    Formal    May I ask you a question?
✅ Use these to ask if something is allowed.
✅ “May” is most formal; “can” is most common in everyday speech.

🔸 MAKING REQUESTS
Modal Expression    Example
Can you…?    Can you help me with this form?
Could you…?    Could you open the window, please?
Would you…?    Would you turn off the lights?
Would you mind + -ing…?    Would you mind closing the door?
✅ “Could” and “Would” = more polite than “Can”
✅ Use Would you mind…? for extra formality (note the -ing form after)

🔹 OFFERING HELP (REVERSED REQUEST)
Expression    Example
Can I help you with that?    Offering assistance
Would you like some coffee?    Offering something
Shall I call a taxi?    Offering to take action
Do you want me to…?    Do you want me to bring anything?

🔸 COMMON RESPONSES
Type    Responses
Granting    Sure!, Of course., No problem., Go ahead.
Refusing    I’m sorry, but…, I’d rather not., I can’t right now.
Uncertain    Let me check., Maybe later., I’m not sure.
✅ Always add “please” or “thank you” for politeness in requests.

🧠 PATTERNS TO PRACTICE
Can/Could/May I + base verb? → Can I borrow your pen?
Can/Could/Would you + base verb? → Could you send me the link?
Would you mind + verb-ing? → Would you mind helping me?

❗ COMMON MISTAKES
Mistake    Correction    Why?
Can I to go now?    Can I go now?    No “to” after modals
Would you mind to open the door?    Would you mind opening the door?    Use -ing form
You can help me?    Can you help me?    Question form needed
I can borrow your pen?    Can I borrow your pen?    Start question with modal

💬 EXAMPLE DIALOG
Emma: Could you help me carry this box?
Tom: Of course! Where does it go?
Emma: Just over there. And may I borrow your marker for a second?
Tom: Sure, go ahead.
Emma: Thanks! Would you mind waiting here for a minute?
Tom: Not at all. Take your time.

13.5 EXPRESSING NECESSITY AND LACK OF NECESSITY
Objective:
To learn how to express what is necessary, not necessary, or optional using modal structures like must, have to, don’t have to, and need to.

🔹 EXPRESSING NECESSITY
Expression    Example Sentence
must    You must wear a seatbelt.
have to / has to    I have to finish this report. / She has to call her doctor.
need to    You need to study for the test.
✅ These express obligation, often with similar meaning.
✅ “Must” is more formal or used in official rules; “have to” is more common in speech.

🔸 EXPRESSING LACK OF NECESSITY
Expression    Example Sentence
don’t have to / doesn’t have to    You don’t have to come early. / He doesn’t have to pay now.
don’t need to / doesn’t need to    We don’t need to bring anything.
✅ Use these when something is not required, but still allowed.
❗ They do not mean “you’re not allowed”—they mean “it’s optional.”

🔹 SUMMARY TABLE
Situation    Expression    Example
Strong necessity    must / have to    You must show your ID.
Obligation    have to    I have to go to work.
Personal need    need to    You need to rest.
No obligation    don’t have to / need to    They don’t have to pay in advance.

🔸 GRAMMAR STRUCTURE
Affirmative    Negative
You have to study.    You don’t have to study tonight.
She needs to leave soon.    She doesn’t need to leave yet.
We must wear helmets.    We don’t have to wear helmets indoors.
✅ Only “have to” and “need to” change with subject (he/she/it).

❗ COMMON MISTAKES
Mistake    Correction    Why?
You must to wait here.    You must wait here.    No “to” after modals
He don’t have to go.    He doesn’t have to go.    Third person + negative = doesn’t
She not need to pay.    She doesn’t need to pay.    Use auxiliary “doesn’t”
You haven’t to do this.    You don’t have to do this.    Wrong negative for “have to”

🧠 PATTERNS TO PRACTICE
I must / have to / need to + verb
You don’t have to / don’t need to + verb
He / She has to / doesn’t have to + verb

💬 EXAMPLE DIALOG
Ryan: Do we have to bring ID for the event?
Zara: Yes, you must bring photo ID to enter.
Ryan: And do we need to wear formal clothes?
Zara: No, you don’t have to. Casual is fine.
Ryan: Great. I need to check the time again.
Zara: It starts at 7, but we don’t have to arrive early.

13.6 USING MODALS IN POLITE LANGUAGE
Objective:
To use modal verbs such as could, would, may, and might to express requests, suggestions, and statements politely and diplomatically in both spoken and written English.

🔹 MODALS FOR POLITE REQUESTS
Modal    Example Request    Politeness Level
Can you…?    Can you send me the report?    Neutral
Could you…?    Could you help me with this?    More polite
Would you…?    Would you close the window?    Very polite
Would you mind…?    Would you mind explaining that again?    Very polite + formal
✅ Could and Would are softer than Can.
✅ Would you mind is followed by verb-ing.

🔸 MODALS FOR POLITE SUGGESTIONS
Modal    Example
Should    You should try the new restaurant.
Could    You could ask for help if needed.
Might want to    You might want to double-check that.
Why don’t you…?    Why don’t you take a break?
✅ Use these to suggest, not command.

🔹 POLITE OFFERS AND INVITATIONS
Modal Expression    Example
Would you like…?    Would you like something to drink?
Can I…?    Can I get you anything?
Shall we…?    Shall we start the meeting?
May I offer…?    May I offer you some assistance?
✅ Use “Would you like…” for invitations.
✅ Use “May I…?” in very formal or professional contexts.

🔸 EXPRESSING UNCERTAINTY OR SOFTENING STATEMENTS
Modal    Example
might    It might be better to wait until tomorrow.
could    We could consider another option.
may    That may not be the best idea.
✅ These make the tone less direct and more respectful or diplomatic.

🧠 USEFUL SENTENCE PATTERNS
Would you mind + verb-ing…? → Would you mind waiting here?
Could you please + verb…? → Could you please help me?
You might want to + verb… → You might want to check that again.
May I + base verb…? → May I speak with you privately?

❗ COMMON MISTAKES
Mistake    Correction    Why?
Can you to help me?    Can you help me?    No “to” after modal verbs
Would you mind to wait?    Would you mind waiting?    Use gerund after “mind”
I want that you explain it.    I’d like you to explain it.    “Want” is too direct; soften with “would like”
You must do this now. (context)    You should probably do this now.    Use modal to soften tone

💬 EXAMPLE DIALOG
Clara: Could you help me with this presentation?
Omar: Of course! Would you like to go over it together now?
Clara: That would be great. Also, would you mind checking the final slide?
Omar: Not at all. And you might want to add a title to slide three.
Clara: Good point. Thanks for your help!

13.7 FUNCTIONAL EXPRESSIONS IN REAL SITUATIONS
Objective:
To use modal verbs and functional expressions in everyday English situations such as giving advice, offering help, asking for permission, and expressing obligations or preferences.

🔹 AT WORK OR IN PROFESSIONAL SETTINGS
Situation    Functional Expression
Making a polite request    Could you send me the document?
Offering help    Shall I forward that for you?
Asking permission    May I join the meeting?
Stating obligation    You must submit the report by Friday.
Talking about necessity    We have to finish this today.
Expressing possibility    We might need more time.
✅ Use could, would, may, must, have to, might depending on tone and context.

🔸 AT A RESTAURANT OR IN A SHOP
Situation    Functional Expression
Ordering food    Can I have the chicken, please?
Asking for options    Could I see the menu again?
Making a request    Would you mind bringing some water?
Offering    Would you like anything else?
Asking for the bill    May we have the bill, please?
✅ “Can I…” and “Could I…” are common in service contexts.

🔹 GIVING ADVICE AND OPINIONS
Context    Expression
Advice    You should get more rest.
Strong advice    You must see a doctor.
Suggestion    You could try a different route.
Polite suggestion    You might want to consider another option.
Personal opinion    I’d recommend taking a break.
✅ Use should, must, could, might, would to vary formality and intensity.

🔸 TRAVEL AND PUBLIC SPACES
Situation    Functional Expression
Asking for directions    Could you tell me how to get to the station?
Asking for permission    Can I take a photo here?
Expressing rules    You must wear a mask on the bus.
Stating lack of need    You don’t have to buy a ticket again.
✅ Adjust tone depending on the situation: informal vs. formal.

🔹 AT HOME OR WITH FRIENDS
Function    Casual Expression
Making a suggestion    Should we order pizza?
Offering    I’ll get the drinks.
Asking help    Can you give me a hand?
Warning/advice    You shouldn’t leave the door unlocked.
Planning    We’re going to watch a movie later.
✅ Even in informal settings, modals help express intentions clearly and politely.

🧠 TIPS FOR USING MODALS IN REAL LIFE
Use “could” and “would” to soften your tone
Use “must” or “have to” for rules and urgency
Use “should” and “might” for flexible suggestions
Combine modals with polite phrases like please, thank you, excuse me

❗ COMMON MISTAKES AND FIXES
Mistake    Correction
You must to bring your ID.    You must bring your ID.
Can I to use your charger?    Can I use your charger?
Would you mind to close the door?    Would you mind closing the door?
She can goes with us.    She can go with us.

💬 EXAMPLE DIALOG
David: Could you help me book a taxi for the airport?
Anna: Sure! Would you like me to schedule it for 6 a.m.?
David: That would be perfect. I must leave early to avoid traffic.
Anna: No problem. Do you want me to bring your coffee, too?
David: If you don’t mind—thank you!

13.8 DIFFERENCES BETWEEN SIMILAR MODALS (MUST VS. HAVE TO)
Objective:
To understand the subtle but important differences between must, have to, and other similar modal verbs when expressing obligation, necessity, or rules.

🔹 “MUST” VS. “HAVE TO”: OVERVIEW
Modal    Typical Use    Example
must    Personal obligation / strong recommendation    You must wear a seatbelt.
have to    External obligation (rules, laws)    I have to pay taxes.
✅ In practice, must and have to are often interchangeable, but their tone differs.

🔸 KEY DIFFERENCES
Context    Must    Have to
Speaker’s opinion    You must see this movie!    Not commonly used for opinion
Legal or external rule    Rare → Visitors must show ID.    You have to wear a uniform.
Written instructions    You must complete all sections.    You have to sign the form.
Spoken everyday English    Less common (sounds formal/strong)    More common in informal speech

🔹 NEGATIVE FORMS
Meaning    Mustn’t    Don’t have to
Prohibition    You mustn’t touch that. (Not allowed)    ✘ Don’t have to = Not prohibition
No obligation    ✘ You mustn’t come if you're tired.    ✔ You don’t have to come if you’re tired.
✅ Mustn’t = not allowed
✅ Don’t have to = optional

🔸 “SHOULD” VS. “MUST”
Function    Should    Must
Advice    You should eat more fruit.    You must eat before the test. (stronger)
Obligation    ✘    ✔ You must complete the form.
✅ Use should for advice, must for obligation.

🔹 SUMMARY TABLE
Function    Modal Used    Example
Strong obligation    must / have to    You must be on time. / I have to work late.
Law or rule    have to    You have to wear a seatbelt.
Personal urgency    must    I must tell her the truth.
Optional action    don’t have to    You don’t have to call me.
Prohibited action    mustn’t    You mustn’t smoke here.

❗ COMMON MISTAKES
Mistake    Correction    Why?
You must to be quiet.    You must be quiet.    No “to” after modal
He don’t have to go.    He doesn’t have to go.    Use correct auxiliary for 3rd person
You mustn’t to eat here.    You mustn’t eat here.    “Mustn’t” is followed by base verb
You must not to do that.    You mustn’t do that.    No “to” after “mustn’t”

💬 EXAMPLE DIALOG
Maya: Do we have to wear formal clothes to the meeting?
Josh: Yes, we have to. It’s the company rule.
Maya: Got it. And we must be there by 9, right?
Josh: Exactly. You mustn’t be late—they’re very strict about timing.
Maya: OK, I’ll set my alarm extra early.

13.9 UNIT 13 REVIEW
Objective:
To consolidate knowledge of modal verbs and their use in real-life communication, covering functions like ability, permission, obligation, advice, offers, and requests.

📘 WHAT YOU LEARNED IN THIS UNIT
🔹 INTRODUCTION TO KEY MODALS
can, must, should, have to
Use modals + base verb: She can speak French.
No “to” after most modals (except have to, ought to)

🔹 EXPRESSING ABILITY AND POSSIBILITY
can = present ability → He can cook very well.
could = past/general ability or polite suggestion
might / could = possibility → It might rain later.
will be able to = future ability

🔹 ADVICE AND OBLIGATION
should / ought to = advice → You should sleep more.
must / have to = strong obligation
mustn’t = prohibited
don’t have to = no obligation

🔹 POLITE LANGUAGE AND REQUESTS
Can/Could/Would you…? = polite requests
May I / Could I…? = asking permission
Would you mind + verb-ing…? = formal and respectful
You might want to… = soft advice

🔹 OFFERS, PROMISES, AND DECISIONS
I’ll help you. → spontaneous offer
I won’t forget. → promise
Shall I…? / Would you like…? → offer/suggestion

🔹 DIFFERENCES BETWEEN SIMILAR MODALS
must vs. have to (internal vs. external obligation)
mustn’t (prohibited) vs. don’t have to (optional)
should vs. must (advice vs. obligation)

🔹 FUNCTIONAL LANGUAGE IN CONTEXT
Used modals in daily life:
→ Can I see the menu?
→ You mustn’t smoke here.
→ You don’t have to bring anything.
→ We should leave soon.

🔹 LISTENING PRACTICE
Focused on identifying:
→ modals in polite requests
→ advice, necessity, and offers in conversation
→ modal use in office, public, and casual settings

💬 EXAMPLE DIALOG
Eli: I have to work late tonight.
Maya: That’s too bad. You should get some rest soon.
Eli: I know. Could you send the client the files for me?
Maya: Of course. And don’t worry—I’ll take care of the follow-up too.
Eli: Thanks! I owe you.
Maya: You don’t have to say that. Just go get some sleep.