English as a Second Language | Modal verbs

Modal Verbs: Adding Flavour to Your Sentences (CEFR B2 Level)

Hello everyone! Welcome to the exciting world of Modal Verbs. Don't worry if these little words sometimes seem confusing—we call them the 'chameleons' of English grammar because their meaning changes depending on the situation!

In this chapter, we will learn how to use modals like can, must, should, and might to express things like ability, permission, obligation, and probability. Mastering modals is crucial for reaching CEFR B2, as they help you communicate attitude and nuance accurately.

What Exactly is a Modal Verb?

Modal verbs are a special type of auxiliary verb (or 'helping verb'). They never stand alone. They always work with a main verb to show the speaker's attitude or judgment about the action.

Think of the main verb (like eat, study, go) as the raw fact, and the modal verb as the spice that tells you how certain, necessary, or possible that fact is.

The Three Essential Rules of Modals

Memorise these three simple rules—they apply to almost all modal verbs (can, could, will, would, shall, should, may, might, must):

1. The Base Form Rule: A modal is always followed by the infinitive without ‘to’ (the base form of the verb).

   Correct: She must study tonight.
   Incorrect: She must to study tonight.

2. No '-s' Rule: Modal verbs never change form for the third-person singular (He, She, It).

   Correct: He can swim very fast.
   Incorrect: He cans swim very fast.

3. The No 'Do/Does' Rule: You do not use do, does, or did to form questions or negatives. The modal does the work itself!

   Question: Can I borrow your pen?
   Negative: You should not worry. (Shouldn't worry.)

Memory Aid: Modals are lazy! They never add -s and they never need do or to after them.

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Section 1: Expressing Ability, Permission, and Requests

These are the foundation stones of modal usage. We use them constantly in everyday conversations.

1. Ability (What you can and cannot do)

• Can: Used for present or general ability.

  Example: I can speak three languages.

• Could: Used for past ability, or for general ability in the past.

  Example: When I was five, I couldn't tie my shoes.

• Be Able To: This is not technically a modal, but it works like one. We use it when can doesn't fit the tense (e.g., future, perfect tenses).

  Example (Future): If you study, you will be able to pass the test.

Quick Tip for Struggling Students: Think of 'be able to' as the universal substitute for 'can'. If you need to use can in the future (like will can), just switch it to will be able to!

2. Permission and Requests (Asking or giving permission)

The choice of modal depends on how formal or polite you want to be:

• Can: Informal/Casual permission (usually between friends or peers).

  Request: Can I leave early? (Casual)

• Could: More polite, tentative, or formal request.

  Request: Could I please use your phone? (Polite)

• May: The most formal way to ask or give permission.

  Request: May I speak to the manager? (Very formal)
  Granting Permission: Yes, you may sit here.

Did you know? In modern English, Can is very common, but many teachers still prefer May when asking formal permission (especially in school settings!).

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Section 2: Obligation, Necessity, and Advice

These modals tell us what we must do, what we should do, and what is forbidden. This section is vital for B2 communication, especially distinguishing between Must and Have to.

1. Strong Obligation and Necessity

Must vs. Have To

Both must and have to mean that something is necessary. However, their meaning changes slightly based on the source of the obligation:

• Must: Used when the obligation comes from the speaker or is a personal feeling/internal decision. It is usually stronger.

  Example (Internal): I must remember my mum's birthday. (The speaker feels this necessity).

• Have To (or Has to): Used when the obligation comes from an external rule, law, or authority (school, boss, government).

  Example (External): Passengers have to show their passports at the gate. (It’s a rule.)

Analogy: Must is your conscience (internal rule). Have to is the written rulebook (external rule).

Note on Past Tense: Since Must has no past tense form for obligation, we always use Had to for past necessity.

Example: Yesterday, I had to finish my homework before dinner.

2. Prohibition and Lack of Necessity

• Mustn't (Must not): Strong Prohibition. This means it is against the rules; you cannot do it.

  Example: You mustn't use your phone during the exam. (Forbidden!)

• Don't Have To (Don't need to): Lack of necessity. This means it is optional. You can do it, but it’s not required.

  Example: You don't have to cook tonight; we can order pizza. (It’s your choice.)

3. Advice and Suggestions

• Should / Ought To: Used for general advice, recommendations, or expressing what is right or ideal. They mean almost the same thing.

  Example: You should save some money for the future.
  Example: We ought to apologise for being late.

• Had Better ('d better): Used for very strong advice, often implying there will be a negative consequence or warning if the advice is ignored.

  Example: You had better leave now, or you'll miss the train!

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Section 3: Possibility and Deduction (Certainty Scale)

This is where modals become tricky at the B2 level. Here, modal verbs are used to express how certain we are about something being true. We call this Deduction or Speculation.

Visualising Certainty (From 100% Certain to 0% Certain)

1. 100% Certain (Fact): He is hungry. (Not a modal)
2. 95%+ Logical Certainty (Strong Deduction): Must

   Used when you are almost sure based on evidence.

   Example: Look at the mud on his boots. He must have been hiking.

3. 50% Uncertainty (Possibility): Might, May, Could

   Used when you think something is possible, but you are not sure.

   Example: I don’t know where David is. He may be at the library or he might be at home.

4. 0% Logical Impossibility (Strong Negative Deduction): Cannot / Couldn't

   Used when you are almost sure something is NOT true.

   Example: That ring cost 50,000 dollars. He can't be wearing it to school!

Important B2 Distinction: Must vs. Must (Deduction vs. Obligation)

• When Must expresses obligation, it means "Required to do." (I must study for the test.)
• When Must expresses deduction, it means "Almost certainly true." (This must be the right road, according to the map.)

Deduction about the Past (Perfect Modals)

To speculate about events that happened in the past, we use the Modal + have + Past Participle.

• Must have + P.P.: You are almost certain it happened.

  Example: The window is broken. Someone must have thrown a ball at it.

• Might/May/Could have + P.P.: It was possible, but we don't know if it happened.

  Example: She looks tired. She might have stayed up late last night.

• Should have + P.P.: Used for criticism or regret (advice about the past).

  Example: I failed the test. I should have studied more.

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Quick Review: Common Mistakes to Avoid

These are the errors that often cost B2 students marks. Check your work against this list!

1. The 'To' Trap: Never put 'to' after the modal (unless the modal phrase is 'ought to' or 'have to', which are exceptions).

   Error: You should to listen. ➡️ Correct: You should listen.

2. The Missing 'S': Never add an 's' to the modal for 'He/She/It'.

   Error: He cans help me. ➡️ Correct: He can help me.

3. Mixing up Mustn't and Don't have to: These have opposite meanings!

   Error: We mustn’t buy milk. (It’s forbidden!) ➡️ Correct: We don't have to buy milk. (We have enough.)

4. Ability in the Past: Use 'Be able to' or 'Could' for the past, not 'Can'.

   Error: Yesterday I can meet him. ➡️ Correct: Yesterday I could meet him. / I was able to meet him.

You’ve covered the most complex parts of modal verbs required for your International GCSE exam. Keep practicing these small, powerful words, and you will see a massive improvement in your fluency and accuracy! Good luck!