What Must You Do? Modal Verbs of Obligation

Today: Learn four ways to talk about obligation, rules, and polite requests: must, mustn't, have to, should, and would like.

Listen to the Feeling

"You must come to the meeting."

"I have to work tomorrow."

"You should eat healthier."

"I would like a coffee, please."

Same idea (obligation or request), but they feel different.

🎙 Speak: Which one sounds the strongest? Which one is the most polite?

Why This Matters

These modals show your attitude. Are you a boss giving an order? Are you politely asking for something? Are you giving advice? Same grammar, different feelings. Let's separate them.

Must & Mustn't: Strong Rules

Use must for strong rules and commands. Use mustn't to say something is forbidden.

The Pattern

Formula: must + base verb

You must arrive on time.
She must read the instructions.
They must not use their phones.

When to Use Must

Strict rules. "You must wear a seatbelt." (The law.)
Strong obligation from authority. "You must be here at 9 AM." (Your boss.)
Your own strong decision. "I must exercise more." (Personal commitment.)

When to Use Mustn't

Forbidden. Not allowed. "You mustn't smoke here." (The rule is clear.)
Very important prohibition. "You mustn't tell anyone." (Keep it secret.)

Key: Must is strong. It's for rules, laws, or authority. Mustn't is "absolutely not."

Real Examples

"You must have a passport to travel." Click

A legal rule. Necessary. No choice. You need the passport.

"You mustn't be late for work." Click

Forbidden. Strongly not allowed. Your boss will be angry.

"I must finish this project today." Click

Your own strong commitment. You've decided it's non-negotiable.

🎙 Speak: Tell me one rule you must follow. Tell me one thing you mustn't do.

Have to & Don't have to: Necessity

Use have to when something is necessary. Use don't have to when something is not necessary (but it's allowed).

The Pattern

Formula: have to + base verb

I have to work tomorrow.
She has to take medication.
We have to leave early.

When to Use Have to

Necessity from a situation. "I have to study for the exam." (It's necessary to pass.)
Doctor's orders. "He has to take three pills a day." (Medical necessity.)
Appointments or commitments. "I have to pick up my daughter at 4 PM."

When to Use Don't Have to

Not necessary, but you can if you want. "You don't have to come tomorrow." (It's optional.)
No requirement. "I don't have to wear a suit to work."

Important: Don't have to ≠ mustn't. Not having to do something is different from being forbidden!

Examples

What's the difference? Click

"You mustn't use the phone in the exam." (Forbidden.)
"You don't have to bring your phone." (It's optional.)
Different meanings! One is a rule. One is just optional.

"I have to go to the dentist next week." Click

It's necessary. An appointment. I cannot skip it.

🎙 Speak: Tell me one thing you have to do. Tell me one thing you don't have to do.

Should & Would like: Advice & Polite Requests

Should gives advice. Would like makes a polite request.

Should: Giving Advice

Formula: should + base verb

You should exercise more.
I should sleep earlier.
She should call her parents.

When to Use Should

Advice or recommendation. "You should try the fish — it's delicious."
What's a good idea. "I should study more for better grades."
What's the right thing to do. "You should be honest with your friend."

Should is weaker than must. It's advice, not a rule.

Would like: Polite Requests

Formula: would like + noun / would like to + base verb

I would like a coffee.
She would like to speak with you.
Would you like to come?

When to Use Would like

Polite requests. "Would you like some tea?" (Not demanding.)
What you want in a polite way. "I would like a table for two, please."
In formal or uncertain situations. "Would you like to join us?"

Would like is very polite. More polite than "I want."

Examples

The difference? Click

"You should call your mother." (Advice. Good idea.)
"Would you like to call your mother?" (Polite question. Maybe you want to.)

"I would like to ask a question." Click

Polite way to ask. More respectful than "I want to ask."

🎙 Speak: Give advice using "should." Make a polite request using "would like."

All Four: Compare & Contrast

Now see them side by side.

The Full Picture

Modal	Strength	Example
must	Strongest rule	"You must wear a seatbelt."
have to	Necessary	"I have to go to work."
should	Advice	"You should exercise."
would like	Polite request	"Would you like tea?"

🎙 Speak: Look at the table. Which is the strongest? Which is the weakest?

Choose the Right One

1. Your doctor: "Take medicine twice a day."

Which modal? Click

have to / must — Medical necessity or strong instruction. "You must/have to take medicine twice a day."

2. Your friend suggests trying a new restaurant.

Which modal? Click

should — Advice or recommendation. "You should try that restaurant."

3. You ask the waiter for water.

Which modal? Click

would like — Polite request. "I would like a glass of water, please."

4. The rule at the office.

Which modal? Click

must / have to — Strong rule. "You must not use your phone during meetings."

🎙 Speak: Create your own sentence for each modal.

Real Situations: Speaking Task

Choose one card. Tell about rules, obligations, and requests for 1-2 minutes.

💼

Your Work Rules

What must you do? What don't you have to do? What should you do?

🏥

Health & Habits

What should you do for health? What do you have to do? What would you like to do?

👨‍👩‍👧‍👦

Family Rules

Growing up, what did you have to do? What must you do now? What should you do for your family?

What to Include

At least one sentence with "must" or "mustn't"
At least one with "have to"
At least one with "should"
At least one polite request with "would like"

2:00

🎙 Speak: Tell me about your obligations and requests. Be real.

What You Can Do Now

I can...

...use must, have to, should, and would like to express obligation, necessity, advice, and polite requests.

Recall Check

1. What's the difference between "must" and "have to"?

Answer Click

"Must" is usually a rule you give. "Have to" is necessity from a situation. Both are strong, but "must" feels more like authority.

2. What does "don't have to" mean? Is it the same as "mustn't"?

Answer Click

No! "Don't have to" = optional. You can if you want. "Mustn't" = forbidden. Not allowed. Opposite meanings.

3. Which is more polite: "I want a coffee" or "I would like a coffee"?

Answer Click

"I would like a coffee" is more polite. "Would like" is formal and respectful. "I want" is direct.

Final Speaking Task

🎙 Speak: Tell me one thing you must do, one thing you have to do, one thing you should do, and one thing you would like to do. Four sentences. Real life.