Modal Verbs: Formation & Conjugation

There are nine modal verbs in English: can, could, may, might, must, shall, should, will, and would. Two of these, will and would, have already been discussed in detail.






1. Formation of the modal conjugations
All of the modal verbs are used as auxiliaries, and all of them form conjugations in the same way. Thus, the other modal auxiliaries form conjugations in the same way as will and would. For instance, the conjugation of the modal auxiliary could with the verb to work is formed as follows:






Conjugations of the modal auxiliary Could with the verb To Work

Simple	Continuous
I could work	I could be working
you could work	you could be working
he could work	he could be working
she could work	she could be working
it could work	it could be working
we could work	we could be working
they could work	they could be working
Perfect	Perfect Continuous
I could have worked	I could have been working
you could have worked	you could have been working
he could have worked	he could have been working
she could have worked	she could have been working
it could have worked	it could have been working
we could have worked	we could have been working
they could have worked	they could have been working

The formation of conjugations using the modal auxiliaries can be summarized as follows:

Conjugation	Auxiliary	Verb Form
Simple	modal auxiliary	bare infinitive
Continuous	modal auxiliary + be	present participle
Perfect	modal auxiliary + have	past participle
Perfect Continuous	modal auxiliary + have been	present participle

Verbs in the Simple conjugation with a modal auxiliary generally refer to present or future time; whereas verbs in the Perfect conjugation with a modal auxiliary generally refer to past time.

Verbs in the Continuous conjugation with a modal auxiliary generally refer to continuous, ongoing actions in present or future time; whereas verbs in the Perfect Continuous conjugation with a modal auxiliary generally refer to continuous, ongoing actions in past time.

The word order for questions and negative statements in the conjugations with the modal auxiliaries is similar to that in other English conjugations.

a. Questions
To form a question, the first auxiliary is placed before the subject. For example:

Affirmative Statement	Question
She can work.	Can she work?
He would be working.	Would he be working?
They should have worked.	Should they have worked?
I could have been working.	Could I have been working?

b. Negative statements
To form a negative statement, the word not is placed after the first auxiliary. It should be noted that the auxiliary can, followed by not, is written as a single word. For example:

Affirmative Statement	Negative Statement
She can work.	She cannot work.
He would be working.	He would not be working.
They should have worked.	They should not have worked.
I could have been working.	I could not have been working.

In spoken English, the following contractions may be used:

Without Contractions	With Contractions
cannot	can't
could not	couldn't
might not	mightn't
must not	mustn't
shall not	shan't
should not	shouldn't
will not	won't
would not	wouldn't

However, it should be noted that the contractions mightn't and shan't are rarely used in modern American English.

c. Negative questions
To form a negative question, the first auxiliary is placed before the subject, and the word not is placed after the subject. However, when contractions are used, the contracted form of not follows immediately after the auxiliary. For example:

Without Contractions	With Contractions
Can she not work?	Can't she work?
Would he not be working?	Wouldn't he be working?
Should they not have worked?	Shouldn't they have worked?
Could I not have been working?	Couldn't I have been working?

d. Tag questions
Tag questions are formed using the first auxiliary. In the following examples, the negative tag questions are underlined.

Affirmative Statement	Affirmative Statement with Tag Question
She can work.	She can work, can't she?
He would be working.	He would be working, wouldn't he?
They should have worked.	They should have worked, shouldn't they?
I could have been working.	I could have been working, couldn't I?

Exercises 1, 2, and 3