Modal Verbs

Modal Verbs

Guide

Modals (also known as modal verbs) are words that come before the main verb.

• ability (can/could/be able to)
• advice (shall/should/ought to)
• necessity (must/have to/need to)
• possibility (may/might)
• will/would
• expectation (be supposed to)

modal + base verb

Modals are always followed by a base verb.A base verb is a verb with no ending(-s, -ed, -ing, etc.) added to it.

Can, Could, Be Able To

Ability/Lack of Ability	can/be able to
Possibility/Impossibility	can
Ask Permission/Give Permission	can

Ability/Lack of Ability

• Present

can/can't	base verb
be/not be able to	base verb

Positive
I/You/We/They/He/She/It	can	play tennis.
I	am able to	help you.
He/She/It	is able to	help you.
You/We/They	are able to	help you.

Negative
I/You/We/They/He/She/It	can't	play tennis.
I	am not able to	help you.
He/She/It	isn't able to	help you.
You/We/They	aren't able to	help you.

Question
Can	I/you/we/they/he/she/it	play tennis.
Am I	able to	write.
Is he/she/it	able to	write.
Are you/we/they	able to	write.

• Future

I/You/We/They/He/She/It	will be able to	help you.
I/You/We/They/He/She/It	will not/won't be able to	help you.
Will	I/you/we/they/he/she/it be able to	help you?

• Past

could/couldn't	base verb
was/were	able to	base verb
was/were	able to	base verb
wasn’t/weren’t	able to	base verb
hasn’t/haven’t	able to	base verb

May, Might

Formal Permission/Formal Prohibition	may/may not+base verb
Polite Request	May+subject+base verb
Possibility/Negative Possibility	may/might+base verb
To Make a Suggestion	may as well/might as well+base verb
Polite Suggestion	might+base verb

Shall, Should, Ought to

To Offer of Assistance or Polite Suggestion	Shall+subject+base verb
To Offer of Assistance or Polite Suggestion	Should+subject+base verb
A Prediction or Expectation that Something Will Happen	should/shouldn’t+base verb
To Give Advice	should/ought to+base verb
To Give Advice (about something you think wrong or unacceptable)	should+base verb

Must, Have to, Need to, Don’t have to, Needn’t

Necessity or Requirement	Present and Future	must/have to/need to+base verb
	Past	had to/needed to+base verb
Almost 100% Certain		must+base verb
To Persuade		must/have to+base verb
Prohibited or Forbidden		must not/mustn’t+base verb
Lack of Necessity		don’t/doesn’t/didn’t+have to+base verb
		needn’t+base verb

Will / Would

	will / won’t + base verb
Polite Request or Statement	Will/Would + base verb
Habitual Past Action	Would/Wouldn’t+base verb

be supposed to

• Present/Futures

expectation.

Class is supposed to begin at 10:00.

• Past

unfulfilled expectation.

Class was supposed to begin at 10:00, but it didn't begin until 10:10.

Summary Chart

AUXILIARY	USES	PRESENT/FUTURE	PAST
may	(1)polite request (only with I or we)	May I borrow your pen?
	(2)formal permission	You may leave the room.
	(3)less than 50% certainty	Where's John? He may be at the library.	He may have been at the library.
might	(1)less than 50% certainty	-Where's John? He might be at the library.	He might have been at the library.
	(2)polite request (rare)	Might I borrow your pen?
should	(1)advisability	I should study tonight	I should have studied last night, but I didn't.
	(2)90% certainty (expectation)	She should do well on the test. (future ends not prevent)	She should have done well on the test.
ought to	(1)advisability	I ought to study tonight.	I ought to have studied last night, but I didn't.
	(2)90% certainty(expectation)	She ought to do well on the test. (future only, nor present)	She should have done well on the test.
had better	advisability with threat of bad result	You had better be on time, or we will leave without you.	(past form uncommon)
be supposed to	(1)expectation	Class is supposed to begin at 10:00.
	(2)unfulfilled expectation		Class was supposed to begin at 10:00, but in didn't begin until 10:15.
must	(1)strong necessity	must go to class today.	( had to go to class yesterday.)
	(2)prohibition (negative)	You must not open that door.
	(3)95% certainty	Mary isn't in class. She must be sick. (present only)	Mary must have been sick yesterday.
have to	(1)necessity	I have to go to class today.	I had to go to class yesterday.
	(2)lack of necessity(negative)	I don't have to go to class today.	I didn't have to go to class yesterday.
have got to	necessity	I' have got to go to class today.	(I had to go to class yesterday.)
will	(1)100% certainty	He will be here at 6:00. (future only)
	(2)willingness	The phone's ringing. I'll get it.
	(3)polite request	Will you please pass the salt?
be going to	(1)100% certainty (prediction)	He is going to be here at 6:00.(future only)
	(2)definite plan (insertion)	I'm going to paint my bedroom. (future only)
	(3)unfulfilled intention		I was going to paint my room, but I didn't have time.
can	(1)ability/possibility	I can run fast.	could run fast when I was a child, but now I can't.
	(2)informal permission	You can use my car tomorrow.
	(3)informal polite request	Can I borrow your pen?
	(4)impossibility(negative only)	That can't be true!	That can't have been true!
could	(1)past ability		I could run fast when I was I child.
	(2)polite request	Could I borrow your pen? Could you help me?
	(3)suggestion(affirmative only)	I need help in math. You could talk to your teacher.	You could have talked to your teacher.
	(4)less than 50% certainty	Where's John? He could be at home.	He could have been at home.
	(5)impossibility(negative only)	That couldn't be true!	That couldn't have been true!
be able to	(1)ability	I am able to help you. I will be able to help you.	I was able to help him.
would	(1)polite request	Would you please pass the salt? Would you mind if I left early?
	(2)preference	I would rather go to the park than stay home.	I would rather have gone to the park.
	(3)repeated action in the past		When I was'a child, I would visit my grandparents every weekend.
	(4)polite for “want" (with like)	I would like an apple, please.
	(5)unfulfilled wish		I would have liked a cookie, but there were Done in the house.
used to	(1)repeated action in the past		I used to visit my grandparents every weekend.
	(2)past situation that no longer exists		I used to live in Spain. Now I live in Korea.
shall	(1)polite question to make a suggestion	Shall I open the window?
	(2)future with "I” or "we" as subject	shall arrive at nine. (will = more common)

Other Source

• Ginger Modal Verbs
• EnglishPage Modal Verbs
• The infinitive after modals