Modals are special verbs that express mood (possibility, necessity, ability, permission, etc.). They are always used with another verb (the main verb) and never change form (no -s, -ing, or -ed endings).

Practice Exercises

Main Modal Verbs:

• can / could
• may / might
• will / would
• shall / should
• must
• ought to (sometimes included)
• used to / need / dare (marginal modals)

Modals’ Key Characteristics

1. No final -s for third person singular:
   • She can swim.
   • She cans swim.
2. Followed by the base form (no “to” except ought to):
   • They must leave now.
   • They must to leave now.
   • You ought to see a doctor.
3. No auxiliary “do” needed for questions/negatives:
   • Can you help? / You cannot go.
   • Do you can help?
4. No infinitive or participle forms (no “to can” or “musting”).

Modals’s Meanings & Uses

1. Ability

Modal	Use	Example
can	present ability	I can speak French.
could	past ability	When I was young, I could run fast.
be able to	replacement for missing tenses	I will be able to come.

2. Permission

Modal	Use	Example
can	informal permission (present/future)	You can leave early.
could	polite permission (less direct)	Could I borrow your pen?
may	formal permission	May I come in?
might	very hesitant/unlikely permission	Might I make a suggestion?

3. Possibility / Probability

Modal	Certainty level	Example
may	50% (possible)	It may rain today.
might	40% (weaker possibility)	She might be late.
could	50% (one possibility)	That could be true.
must	95% (logical deduction)	He must be at work (lights are on).
can’t	0% (impossibility)	She can’t be 80 – she looks 40.

4. Necessity / Obligation

Modal	Use	Example
must	strong internal obligation	I must call my mom today.
have to	external obligation (rules)	You have to wear a helmet.
must not	prohibition	Students must not cheat.
need to	necessary action	You need to study more.
should / ought to	advice / weak obligation	You should eat less sugar.

5. Requests & Offers

Modal	Example
can	Can you pass the salt? (informal request)
could	Could you please repeat that? (polite)
would	Would you like some coffee? (offer)
will	Will you open the window? (request)
shall (I/we)	Shall I close the door? (offer/suggestion)

6. Habits (Past)

Modal	Example
would (past repeated actions)	Every summer we would go to the beach.
used to (past states + actions)	I used to live in London.

7. Predictions

Modal	Example
will	It will be sunny tomorrow.
would (past future)	He said he would arrive at 8.

Negative Forms & Contractions

Modal	Negative	Contraction (common)
can	cannot	can’t
could	could not	couldn’t
may	may not	(no contraction)
might	might not	mightn’t (rare)
will	will not	won’t
would	would not	wouldn’t
shall	shall not	shan’t (rare)
should	should not	shouldn’t
must	must not	mustn’t

Past Forms of Modals

Use modal + have + past participle

Expression	Meaning	Example
could have done	past ability not used	I could have won, but I tripped.
might have done	past possibility	She might have missed the bus.
must have done	strong past deduction	He must have left early.
should have done	past advice not followed	You should have studied.
needn’t have done	unnecessary past action	You needn’t have cooked.

Common Mistakes to Avoid

• Using “to” after most modals: She can swim (not can to swim)
• Using two modals together: You will be able to go (not will can go)
• Adding -s for third person: It must work (not musts)
• Using “did” in negative past modals: She couldn’t come (not didn’t could come)

Quick Comparison Table

Tense/Function	Positive Example	Negative Example
Ability (present)	I can swim.	I cannot swim.
Ability (past)	I could swim.	I couldn’t swim.
Permission (polite)	May I sit here?	You may not enter.
Obligation (strong)	You must go.	You mustn’t go.
Advice	You should rest.	You shouldn’t smoke.
Possibility (present)	It may snow.	It may not snow.
Deduction (present)	He must be tired.	He can’t be tired.

Practice Exercises