Modal verbs are powerful tools in English grammar that allow you to express attitudes, judgments, and subtleties—exactly what the IELTS exam is designed to test, especially in Writing Task 2 and Speaking Parts 2 and 3. This comprehensive guide will help you not only understand modal verbs but also use them confidently in both academic and spoken contexts.
What Exactly Are Modal Verbs?
Modal verbs are defective auxiliary verbs—which means they do not inflect (change form) like regular verbs, and they cannot stand alone. They always work in combination with a main verb in base form, and they allow the speaker or writer to indicate possibility, probability, permission, necessity, ability, or willingness.
Unlike other auxiliaries, modal verbs:
- Do not take “-s” in the third person (e.g., He can, not cans)
- Do not use “to” before the verb (with few exceptions)
- Do not have infinitive, participle, or gerund forms
Detailed Classification of Modal Verbs
1. Modals of Ability
- Can / Could / Be able to
- I can solve this problem.
- He could swim when he was five.
- She is able to manage the team well.
2. Modals of Permission
- Can / May / Might
- You may leave now. (Formal)
- Can I ask a question? (Informal)
- Might I use your phone? (Very polite)
3. Modals of Obligation and Necessity
- Must / Have to / Need to / Should / Ought to
- You must wear a seatbelt. (Strong obligation)
- She has to finish it today. (Requirement)
- You should drink more water. (Advice)
4. Modals of Possibility and Probability
- May / Might / Could / Can / Must / Should
- It may snow tomorrow. (Possibility)
- He must be tired after the flight. (Strong deduction)
- You could be right. (Tentative possibility)
5. Modals of Advice or Recommendation
- Should / Ought to / Had better
- You should prepare for all sections equally.
- We ought to review our answers.
6. Modals of Habit (Less Common)
- Will / Would
- Every evening, he would go for a walk.
- She will often stay up late studying.
Modal Verb Structures
Positive Form
Subject + Modal + Base Verb
He might go to the event.
Negative Form
Subject + Modal + Not + Base Verb
They should not eat so late.
Interrogative Form
Modal + Subject + Base Verb
Can you help me?
Should we wait?
Modal Verbs vs. Semi-Modal Verbs
| Modal Verb | Semi-Modal Verb |
|---|---|
| must | have to |
| can | be able to |
| should | ought to |
| may/might | be allowed to |
Note: Semi-modals behave more like normal verbs and require conjugation.
Advanced Modal Forms: Modal Perfect and Modal Continuous
1. Modal + Have + Past Participle (Perfect Form)
Used for past probability, criticism, or lost opportunities:
- You should have called me.
- He might have forgotten the time.
- They must have left already.
2. Modal + Be + Verb-ing (Continuous Form)
Used for ongoing or interrupted actions with modality:
- He must be joking.
- She might be sleeping now.
Using Modals in IELTS Speaking
Part 1 Tip: Use can, might, would to express general habits and preferences
I can usually relax by listening to music.
I might go hiking next weekend.
Part 2 Tip: Use a range of modals to describe hypothetical situations or past events
If I had the chance, I would definitely study abroad.
I could have chosen a different path.
Part 3 Tip: Use modal verbs to express opinions and analysis
Governments should regulate advertising more strictly.
People might become too reliant on smartphones.
Common Errors and How to Avoid Them
| Error | Why It’s Wrong | Correct Usage |
|---|---|---|
| He musts do it. | Modals don’t take “-s” | He must do it. |
| Can to help | “To” is not used after modals | Can help |
| She may goes | Main verb must be base form | She may go |
| Should to eat | “To” is unnecessary | Should eat |
Modal Verb Dos and Don’ts
Dos
- Use modal verbs to express certainty, advice, and opinions in IELTS Writing.
- Practice modal perfect and continuous forms for advanced grammar range.
- Combine modal verbs with collocations:
- can afford, should consider, must complete
Don’ts
- Don’t use double modals (e.g., might can, would must).
- Don’t use “to” after true modals (must to, can to).
- Don’t forget to pair with base verbs only.
IELTS Grammar FAQs About Modal Verbs
Q: Can I use modals in academic writing?
A: Yes, especially for hedging, suggesting, and analytical reasoning.
Q: Are modal verbs formal or informal?
A: It depends. “Can” is informal; “may/might” are more formal or polite.
Q: How can I show a high grammar range in IELTS?
A: Use a variety of modal verbs in different tenses and forms (e.g., could, should have, must be).
IELTS Writing Task 2 Sample Using Modals
Governments must prioritize education, as it is the cornerstone of national progress. While individuals may choose alternative career paths, society should ensure that equal opportunities are available to all.
Vocabulary Collocations with Modals
- Should encourage
- Must address
- Might contribute
- Could prevent
- Can improve
Self-Practice Ideas
- Rewrite Sentences with Modals
- Change a base sentence into 3 variations using different modal verbs.
- IELTS Essay Challenge
- Write an opinion essay using at least 10 different modal verbs or forms.
- Speaking Simulation
- Record answers to common IELTS Speaking questions using “could,” “might,” “would,” and “should.”
Further Study with IELTS Guide Phil
To reinforce everything you’ve learned, tune in to:
- IELTS Guide Phil Podcast on Spotify
- Episode: Grammar Range Secrets for Band 7+
- Episode: Modal Verbs in IELTS Writing: Do’s and Don’ts
- ieltsguidephil.com
- Download free grammar eBooks and modal verb worksheets.
- Follow IELTS Guide Phil on
Facebook | X (Twitter) | BlueSky
for daily IELTS grammar tips and quizzes.
Final Thought
Mastering modal verbs will not only improve your sentence structure and accuracy but also help you express complex ideas and opinions—a key requirement for achieving a Band 7.0 or higher in IELTS.
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