A “Brief” Modal Verb Overview

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Modal verbs are special verbs (some people consider them auxiliaries) that allow you to transmit additional information, expression or nuance to the main verb of your sentence. While modal verbs provide a rich variety of communicative uses, using them is not always straightforward. In this overview, we will revise the governing grammar and the many different ways you can use them to express yourself more accurately.

  • Must
  • Must not
  • Can / Can’t
  • Could / Couldn’t
  • May
  • Might
  • Need not
  • Should / Shouldn’t
  • Ought to / Ought not to
  • Had better
  • Would / Wouldn’t
  • Will / Shall


  1. They don’t change form. You will never conjugate them in any tense: no “-s/-es” present endings, no “-d/-ed” past endings, and no gerunds.

Incorrect: She could plays games online.

Correct: She could play games online.

2. They are almost always followed by the base form of the verb (infinitive without “to”), even in more complex constructions like  2nd and 3rd conditionals.

Incorrect: He should to work on the website.

Correct: He should work on the website.

3. You cannot combine them with  “do” and “be” auxiliaries.

Incorrect: I am could be a designer.

Correct: I could be a designer.


MUST = Strong obligation / Logical conclusion with a lot of certainty


You must do what is outlined in the contract.

They must follow the terms on the website.

Logical conclusion:  in this case, we use the perfect modal form: must + have + V3 because it is a supposition about a past situation

She must have talked to the clients; it’s already noon.

You must have found a solution for the bug, as the program runs well now.

MUST NOT (MUSTN’T) = Prohibition / Logical Conclusions


You must not use copy those designs.

The chief must not see these changes before the program is launched.

They mustn’t talk to him if they don’t want to mess up the new deal.

Logical conclusion: Like “must” in the positive, we also use the perfective modal form for the negative:  must not + have + V3

She must not have finished the designs. I don’t see anything in the folder.

The work team must not have understood the issues, since they are still there.

They must not have updated the new software; the old one is still in the system.

CAN/CAN’T = Ability / Permission / Possibility


You can code incredibly!

She can’t manage social networks; others do it better.

Casual Permission

Can I purchase some cryptocurrency on this website?  Yes, you can.

Can we make these changes to the platform, boss?  Yeah, go ahead.

Possibility (present or future only)

I think we can finish this set-up by tomorrow or on Sunday.

The team probably can’t develop this engine without any help.

COULD/ COULDN’T = Ability in the past / Polite Permission / Possibility

Past ability

I could develop my own website when I was a kid, but now it’s too complicated.

They couldn’t finish the projects because they had many obstacles.

Polite permission

Could we make some modifications to the patent description? – Yes, sure.

Could I make some changes to the document? – Sure, go ahead.

Future possibility

The platform could be ready by Monday.

The proposal could be delivered during the next meeting.

The Judge could postpone the hearing.

Past possibility: use the perfect modal form: could + have + V3

He could have concluded the report, but I haven’t seen it yet.

They could have fixed the firewall issues, but I ran out of time.

She could have arrived already. I will check.

MAY/MIGHT = Polite permission / Possibility / Probability

Polite permission

May I speak to you about the new project? – Yes, you may.

May I leave the document like that? No, you may not. Make the required changes.

Possibility (indicating something could happen in the future; it’s an option)

I may go to the networking event, but I’m not sure yet.

We might have a problem with this transaction, but we don’t know yet.

Probability (indicating something is very likely to happen in the future due to evidence)

There may be some changes soon, the bosses are planning something.

She might help you with the next project because she is very interested in it.

! NOTICE: Yes, they mean the same thing, but “may” is more formal and polite than “might”.  “May” is often more commonly used for permissions.

NEED NOT = No necessity/obligation (formal, not common)

No necessity/obligation

I need not finish this for today; it can be done tomorrow.

I need not use this particular trading website; I know a  better one.

I need not do this, because she’s already done it.

! NOTICE:  We usually say “don’t need + TO DO + something” (I don’t need to file a trademark application.) to express the same meaning in a more modern way.

SHOULD / SHOULDN’T = Advice/suggestion / Logical conclusion with some certainty


He should consult with his supervisor about this issue.

The salespeople shouldn’t harass their clients with too many proposals.

Logical conclusion: use the perfect modal form should + have + V3  to express logical conclusion in the past

It’s late now; he should have finished the revisions to the copyright applications.

She should be in constant contact with all supervisors; it’s her job!

OUGHT TO / OUGHT NOT TO = Advice/suggestion


They ought to make some changes to the streaming player.

We ought not to modify the code much, as it works quite well.

HAD BETTER = strong advice/ warning

You’d better check on the new patent protocols to avoid any problems.

She’d better fix that bug or we will be in serious trouble.

The lawyers had better double check those IP documents before they make any decisions.

WOULD / WOULDN’T = Wishes / Polite request / Habits in the past


I would go to the market if I could!

I wish the client wouldn’t send me 200 emails each day.

Polite request

Would you please discuss these infringement claims with our clients? – Yes, I will.

Would you help me with this issue? Sorry, I can’t right now!

Past habits

When I was a junior associate, I would (often) work 15 hour days, but not anymore.

At first, the enterprise wouldn’t use any new cryptocurrencies, but now it’s more open to them.

WILL / SHALL  = to talk about future events /plans

I will make the changes and present the plan to the new boss.

They shall come to the office tomorrow to discuss the new IP law.

He won’t be coming to the meeting new week.

We shall not be dealing with this problem anymore.

! NOTICE:  “shall” is much more formal and commonly referred to as an “archaic term”. It’s so formal, it’s actually funny.  It’s best to just use “will”.

And there you have it! If you have questions, please write me a note!