✦ B1 Level

Modal Verbs: Nuance and Politeness

Use modals to express ability, obligation, permission, advice, and possibility with greater precision.
4.1 — Can, Could, Be Able To: Ability Across Time
4.2 — Must, Have To, Should, Ought To: Obligation and Advice
4.3 — May, Might, Could: Possibility and Uncertainty
4.4 — Must Not vs. Don’t Have To: Prohibition vs. Lack of Obligation
4.5 — Modal Verbs in Questions and Requests (Could you…? Would you…?)

1

4.1 - Can, Could, Be Able To: Ability Across Time

Expressing ability in the present, past, and future
📌

Can is used for present ability. Could is used for past ability. Be able to can be used in all tenses (present, past, future, perfect).

Form: can / could + base verb OR be able to + base verb
Use Signal Words Example
Can present ability "I can speak three languages."
Could past ability "I could swim when I was five."
Be able to all tenses "I will be able to help you tomorrow."
Can / Could + base verb
Be able to + base verb (any tense)
I can speak English quite well now.
Present ability.
When I was younger I could run very fast.
Past ability.
I have never been able to play the piano.
Present perfect.
One day I will be able to speak French fluently.
Future ability.
2

4.2 - Must, Have To, Should, Ought To: Obligation and Advice

Strong obligation, necessity, and giving advice
✅

Must and have to express obligation. Should and ought to give advice or recommendations (less strong than must).

Must / Have to = obligation
Should / Ought to = advice
You must wear a helmet when riding a motorbike.
Strong obligation (rule).
I have to finish this report by Friday.
External necessity.
You should drink more water every day.
Advice.
You ought to apologise to her.
Mild advice (formal).
3

4.3 - May, Might, Could: Possibility and Uncertainty

Expressing possibility and speculation
⚠️

May and might express possibility. Could can also express possibility (especially in the past or with less certainty).

It may rain later this afternoon.
Possible future event.
She might be late because of the traffic.
Speculation.
He could be the new manager — I’m not sure.
Possible identity.
4

4.4 - Must Not vs. Don’t Have To: Prohibition vs. Lack of Obligation

Important difference between prohibition and no necessity
📌

Must not = prohibition (it is forbidden). Don’t have to = no obligation (it is not necessary).

Never say “mustn’t have to” — the two expressions are completely different.
You must not use your phone during the exam.
Prohibition (forbidden).
You don’t have to wear a suit — it’s casual Friday.
No obligation.
5

4.5 - Modal Verbs in Questions and Requests (Could you…? Would you…?)

Polite questions and requests
✅

Use could and would to make polite questions and requests. They sound softer and more polite than “can” or “will”.

Form: Could / Would + you + base verb…?
Could you help me with this report, please?
Polite request.
Would you mind opening the window?
Very polite request.

Practice Quiz — B1 Level

20 questions selected from a pool of 50 · Modal Verbs: Nuance and Politeness · Click your answer for instant feedback

Choose the correct modal verb (or form) to complete each sentence. Think about nuance, politeness, obligation, possibility, etc. Click your answer for immediate feedback.

Copyright © 2026 – Prof. E. A. Aguilar Ramírez • CUU English / Spanish Language Center • All rights reserved.
This educational material is designed and compiled exclusively for CUU English/Spanish Language Center students and may not be reproduced without permission. It is protected by international copyright laws, including the Berne Convention and applicable national legislation. Unauthorized reproduction, distribution, modification, or commercial use of any part of this material is strictly prohibited without prior written permission from the author.
www.inglescuu.com