Modal Auxiliary Verbs
(Present)

The most common auxiliary verbs are "be," "do," and "have", and you may also use
these verbs on their own. Other common auxiliaries are "can," "could," "may,"
"might," "must," "ought," "should," "will," and "would." A verb like these is called a
modal auxiliary and expresses necessity, obligation, or possibility.

Most common
Auxiliary Verb

Present

I do work.

I have worked

I have been working.

Can is a auxiliary
Verb

We use can to

•talk about possibility and ability


• make requests


• ask for or give permission

Modal Auxiliary Verbs
Past

The highlighted word in each of the following sentences is a modal auxiliary

Example

Zora was pleased to learn that she could take several days off.


The small freckled girl told her neighbors that she would walk their dog for an
appropriate fee.

Estructure of could

Subject + could + main verb

Use of Could

Could: Past Possibility or Ability

We use could to talk about what was possible in the past, what we were able or
free to do:

• I could swim when I was 5 years old.


• My grandmother could speak seven languages.


• When we arrived home, we could not open the door.