What
Are Modal Auxiliary Verbs?
Modal auxiliary verbs are used to show a necessity, capability, willingness, or
possibility. Unlike most verbs, there is only one form for these verbs.
Typically, verb forms change to indicate whether the sentence's subject is
singular or plural.
Most verbs also indicate whether
something happened in the past, present, or future. This is not the case with
most modal auxiliary verbs, which makes them simpler to understand and use
correctly.
Examples
of Modal Auxiliary Verbs
So now that we understand the
purpose of modal auxiliary verbs, let's take a look at some of the common ones
you may see in writing. The modal auxiliary verbs include:
- Can
- Could
- May
- Might
- Must
- Ought
- Shall
- Should
- Will
- Would
 |
It's important to note that these
verbs can also indicate the negative: could not, may not, should not, etc.
Indicating
Past Tense with Modal Auxiliary Verbs
Since modal auxiliary verbs do not
have a past tense form, we can use the modal auxiliary along with the word
'have' and a past participle. Past participles typically end in -d, -ed,
-n, or -en, creating the past tense 'wished, looked, taken' and so forth. Let's
take a look at an example in the present tense.2 Let's say I'm at the store in
the produce section:
- I should buy another pound of potatoes.
When I come home from the grocery
store and realize that my potato bin is empty, I will use past tense. To change
this sentence, which currently uses the modal auxiliary verb 'should,' to past
tense, we would follow the rule above.
Examples of modal auxiliary verbs
Before we look at some of the possible meanings
of modal auxiliary verbs we need to have some idea of what constitutes a modal
in English and where they occur in a sentence. A few more examples should
enable us to answer the second of these points fairly quickly and easily – the
modals are in bold:
- He should be here by now.
- I could swim quite well when I was younger.
- You mustn’t blame yourself for this.
- You might have discussed it with me first.
- You can’t be serious!
- Could you open the window please?
- Must you make so much noise?
- She had to take her brother along with her.
- We ought to be going.
It should be clear from these examples that the
modal verb occupies the first position in verb phrase, coming before any other
auxiliary verb (like have or be) and the main lexical verb.
In questions the modal verb is simply inverted
with the subject of the sentence as in examples 6 and 7 and it also carries the
negative particle not (3rd and 5th examples).
The subject of the sentence has no effect on the
form of the modal since almost in all cases they do not change at all.
So, a modal verb is quite simple as far as its
form and position in various types of sentence are concerned; but what exactly
are the modal verbs in English? The chart below lists the main modal
auxiliaries that you are likely to meet and divides them into two categories pure
modals and semi-modals, although in most cases the distinction is
merely formal and their meanings are not affected by this division.
Pure modals |
Semi-modals |
|
can
|
ought to
|
|
could
|
has/have (got) to
|
|
may
|
be able to
|
|
might
|
|
|
shall
|
|
|
should
|
|
|
will
|
|
|
would
|
|
|
need ***
|
*** need is a special verb since as an
auxiliary it is almost always negative and it is also a lexical verb as in
sentences like he needs to speak to you now, while it acts as a modal
verb in sentences such as you needn’t come to work tomorrow where it
has the same meaning as don’t have to.
The forms of pure modals
The main characteristics of the pure modals are:
- they
never change their form irrespective of the subject of the sentence
e.g. he can swim, not *he cans swim - following
on from the above feature, they do not change to show past tense
e.g. she had to leave not *she musted leave - they
all carry the negative of the sentence by the addition of not/n’t
e.g. I can’t remember not *I don’t can remember - they
all form questions by inversion with the subject of the sentence.
e.g. should I stay? - they
are all followed by the base form of the verb without the addition of to
e.g. he can swim not *he can to swim
The forms of semi-modals
You will notice that this type of modal is made
up of two or more separate words, the last one invariably being to.
They are all modal in meaning but not in form as they behave differently in a
sentence from the pure modals. It is perhaps best to think of the semi-modals
in the form with the toinfinitive that is given in the table rather
than thinking of them as modals that need to + base form. We need to
look at the form of each individual semi-modal separately.
Be able to
We use this semi-modal to express possibility or
the ability to do something, but unlike the pure modals, be able to
has a full range of tenses and also needs to inflect to show agreement with its
subject. For example:
- He is able to offer you the best price possible.
- We were able to get in to see the film.
- They haven’t been able to find the missing document.
- So, you aren’t able to help.
Notice that the negative is carried either by the
be element or the auxiliary verb that is closest to the subject of the
sentence. It can also be accompanied by any of the pure modals:
- I will be able to see you after lunch.
- They might not be able to put us up for the night.
Has/have (got) to
This is used to express necessity or obligation
to do something and shares some of the features ofbe able to discussed
above. The have element of the form has to change to agree with its
subject. Although it is normally used in the present tense, it also has its own
past (had to) and can be used with pure modals to show the future or
the attitude of the speaker:
- They have to be more punctual.
- He has to take responsibility for the accident.
- I had to help my father repair his car.
- We will have to put this off until tomorrow.
- You shouldn’t have to suffer in silence.
- You don’t have to come if you don’t want to.
- He didn’t have to do all the shopping.
From these few examples it should be clear that the
negative not again attaches itself to the auxiliary verb (modal or
main) that comes immediately after the subject of the sentence.
Ought to
It is usually claimed that the meaning of ought
to is the same as should whether it refers to giving advice or making
a logical deduction. So, to most native speakers the following sentences withought
to and should feel the same:
- You ought to see a doctor.
- You should see a doctor.
- They ought to have got back home by now.
- They should have got back home by now.
In practice, most speakers tend to prefer should
for negatives and questions because the ought toand oughtn’t … to
forms can sound rather clumsy and awkward.
- Ought you to be doing that?
- They oughtn’t to (ought not to) do that.
- Oughtn’t we to leave now?
Meanings of modal verbs
The main function of modal verbs is to allow the
speaker or writer to express their opinion of, or their attitude to, a
proposition. These attitudes can cover a wide range of possibilities includingobligation,
asking for and giving permission, disapproval, advising, logical deduction,
ability, possibility, necessity, absence of necessity and so on. The
problem with each modal verb is that it can have more that one meaning and the
interpretation of a particular modal will depend heavily on the context in
which it is being used. The following examples should help to illustrate this
point.
- It might take more than a week. (possibility)
- You might have told me about it! (showing disapproval)
- He must take his medicine three times a day. (obligation)
- He must be French. (logical deduction)
- I can’t lift that suitcase by myself. (ability)
- That can’t be the right answer. (logical deduction)
- May I look at the questions now? (asking for permission)
- They say it may snow tomorrow. (possibility)
You probably also noticed from the examples that
notions like permission and possibility can be expressed
using different modal verbs – this, of course, only serves to complicate
matters further since one modal verb can have more that one meaning, and one
meaning can be expressed by more than one modal verb. In the space that we have
available here it would be impossible to cover all the meanings of each of the
modals, so as examples we will look at some of the ways thatobligation
and logical deduction can be expressed.
Obligation
The two main modals here are must and have
to. The difference between them is usually given as follows: must
is used to express an internal obligation that is imposed by the speaker, while
have torefers to rules and regulations that are imposed from outside
the speaker. Again, as with many points of grammar this is only intended as a
rough guide.
To express a lack of obligation we cannot just
automatically add not to the modal verbs without thinking more
carefully about it first. How do you feel about the following sentences for
instance?
- He must sing loudly.
- He mustn’t sing loudly.
In the first sentence you would probably agree
that this is obligation originating from, say, a teacher or someone
with authority. The second sentence, however, does not express a lack of
obligationbut a prohibition to do something. The form that we use
to express a lack of obligation could be one of the following:
- He doesn’t have to get up early.
- He doesn’t need to get up early.
This lack of balance in the use of modals can
cause many problems for people who are learning English since it is quite
illogical.
Logical deduction
This is another area of modal use that is fraught
with difficulties for reasons similar to those just discussed above. Look at
the following sentences:
The telephone rings:
- That’ll be Frank.
- That must be Frank.
- That should be Frank.
- That could be Frank.
- That might be Frank.
- That may be Frank.
The modal verbs used here have been listed in
what many consider to be the order of likelihood of something being true. You
may or may not agree with this listing, but it gives you some idea of some of
the choices available for drawing logical conclusions from situations. If we
look at the negatives of these sentences, however, you can see just how much
more complex it can become:
- That won’t be Frank.
- *
That mustn’t be Frank.
(To use musn’t in this way as logical deduction is incorrect; we use can’t instead.) - That shouldn’t be Frank.
- That couldn’t be Frank.
- That mightn’t be Frank.
Many of these sentences now denote completely
different attitudes to the situation and you may even agree that some of them
are either not English or are only marginally acceptable. The sentence which
has probably moved furthest from its original intention is the second one
(mustn’t) which sounds very odd. In fact, the negative of must when we
talking about deduction is can’t – one more example of how complicated
and counter-intuitive the system of English modals can be.
Past time with modals
We noted earlier that the pure modals do not
change to show tense. Most of these modals do in fact have either present or
future reference, but sometimes we need to refer back to the past. With the
semi-modals there is little problem, but how can we do this for pure modal
verbs? You may have picked up from some of the previous examples that one way
to do this is to insert have immediately after the pure modal. But
this is not always the case since can has its own past tense could
when it refers to general ability. Some examples should help:
- I can speak German.
- I could speak German when I was seven years old.
- You should see this film.
- You should have seen this film.
- Indonesia must be hot.
- Indonesia must have been hot.
- He could find his wallet.
- He could have found his wallet.
Notice that in the third pair of sentences the
meaning of must is logical deduction not obligation. If we want to use
must for obligation then the past tense is had to.
- She must visit her mother.
- She had to visit her mother.
