Modal verbs | The parts of speech | Grammar

- [Voiceover] Hello grammarians!

Today we're gonna talk
about a class of auxiliary,

or helper verbs, called the modal verbs.

These are verbs that
have special properties

and help other verbs.

But what is modality?

My fellow grammarian,
I am so glad you asked.

Modality is when we use
these verbs to express

conditions on stuff.

So we can use these verbs
to determine if something

is likely to happen, or
certain to have happened.

Whether or not something is possible,

or whether or not we have
the ability to do something.

Whether or not we have the
permission to do something.

And whether or not we have the obligation

or requirement or need to do something.

You already know all of
these verbs, I promise you.

You just didn't know this name for them.

Let's meet the modals.

Roll call, here we go.

May, might, must, can,

could, shall, should,

will, would.

Those are the modals.

So here's what modal verbs can do.

Thing number one, they
agree with everything.

So you can take any one of these modals

and you can use any subject in the world

and it's not gonna change, right?

You take a word like talk, for instance,

and you would say I talk,

Diane talks.

Right, you add the s.

But any subject in any
sentence is going to take

the modal verb the same way.

Let me show you.

I can do it, you can do it,

she can do it, they can do it,

we can do it.

It's all the same.

They agree with everything.

Something else that modals
do is actually something

that they don't do.

They don't have a to form,

this is what we call the infinitive.

So there's no such thing as to may,

or to could.

That just doesn't exist.

So modals don't have infinitives.

You can't say I want to should.

That is an illegal operation in English.

It is ungrammatical.

It doesn't matter what
version of English you speak,

across all varieties of
English you cannot to should.

And finally, a thing
that modal verbs can do

is indicate modality.

Which, like we said,
establishes conditions.

So let's take a look at some examples.

So the word must, right?

We can use the word must
in a couple different ways.

So, if you imagine a
detective looking up from some

tracks, some muddy
bootprints on the floor,

with her magnifying glass.

She looks up and she says
"He must have gone that way!"

That detective is using must
to express a likelihood,

a high likelihood.

This must have happened.

But if you're at an amusement park

and the roller coaster you
want to ride has a height

requirement, the sign probably says

"You must be this tall to
ride the Doom-Coaster."

This is like a necessary condition.

By a similar token, if
you enter someone's house

and they demand that
you take off your shoes,

they would say "You
must remove your shoes."

Similarly with may, we
can use may to express

a possibility, like saying "It may rain."

That's something that
could possibly happen.

Or to give someone permission, like

"You may enter."

You can use a word like
can to express ability.

You could say "I can eat
ten pounds of broccoli!"

And that's expressing your
ability to do a thing.

We also use modal verbs
like this to talk about

conditions, or stuff that
isn't going to happen

or maybe could happen.

And so, for example, in
this sentence, we would say

"I would make the bed, but I'm tired."

Because the possibility
exists, however remote,

that the bed would be made by me,

but I don't feel like it.

So I'm using would to offer an excuse,

I'm saying this could possibly
happen, this would happen,

except for this one other problem,

which is that I'm sleepy.

You can also use modal
verbs to give advice

to someone, as in "You shouldn't do that."

And something that is special to will,

and, to a lesser extent, shall,

is that they can form the future.

Shall used to be a lot more popular,

and it still is in British
English, but less so

in standard American.

So would say "He will
win the competition."

Or "He shall win the competition."

And use of this modal verb will, or shall,

indicates that that thing
that you're talking about

is happening in the future.

These verbs are very powerful.

You should learn how to use them

and in fact if you can
complete the exercises,

then you will master these tricky verbs.

You can learn anything.

David out.