verbs of ability : can and may
verbs of ability are used to express two different types
of ability: open possibility, generally expressed by forms of the modal
verb Can, and
authority or potential ability, generally expressed by forms of the
modal verb May.
These two verbs are followed by the infinitive
and be able to
The verb can
in the simple present, simple past and present perfect forms.
not, cannot, can't
If other tenses are required, the speaker or writer must use forms of
the synonymous modal verb "be able
to" . This modal auxiliary has all necessary
tenses, as it is in reality just the verb to be
followed by the adjective able.
N.B. : Be able
to does not have any progressive or continuous forms.
||am able to,
been able to
have been able to
were able to
be able to
not able to ,
am unable to
not been able to
has been unable to
not able to
was unable to
will be unable to
Can and able to
are used to express :
a. Physical or potential ability
b. Authority to do something (by confusion with may)
c. Can only: in the present perfect, a past possibility. This is
particularly common with negative clauses.
can speak three different languages, English, French and
a2) He can't open the door, it's stuck.
a3) I'm able to speak three languages, German, English and
a4) He's unable to get into his car, he's lost the key.
a5) When I lived in York, I could walk to work in five
a6) If you lose the key, you won't be able to get
into your apartment.
a7) I haven't been able to finish the job, it's too difficult.
a8) In spite long discussions, they were unable to reach an
b1) The policeman says we can go in now.
b2) Can we please sit down !
c1) They cannot have seen the warning sign.....
Take care to distinguish correctly between "could not" and
They could not see the warning
were unable to see it, for example, because it was hidden
cannot have seen the warning sign.....
must have failed to see it, even though it was there and visible.
possibility or authority - may
The verb may only exists
in the simple present, and past forms The simple past form of may is
is also used in its own right as a
present tense modal.
Forms of may
Forms of might
||may not have
||might not have
a) The modal may is
used to imply potentiality (limited possibility) or authority to do
something. Using the modal may
is frequently the same as qualifying a statement with the word perhaps.
Its past form might
is most commonly found in dependent clauses, notably in reported speech.
Note that a synonym
which is of course composed of the words may
b) Used in the present perfect form (may + have + past
is also used to express possibility
that occurred (something that perhaps occurred) in a relative past
, i.e. in past time with relation to the present or to some other
is also used to imply remote
possibility, i.e. something that could just be possible. In this sense,
it is often combined with be
d) Used in the present
perfect (might + have + participe
is also used to express a hypothetical possibility
(affirmative or negative) in the past. This is particularly common in
type 3 conditional clauses.
and may can
both be used to imply politeness or sarcasm.
may (perhaps) go to England next year, if we have enough money.
a2) But of course, we may not be able to afford it.
a3) The policeman said "You may go now".
a31) The policeman told me I might go.
a4) "I may not be able to get home on time."
a41) She said she might not be able to get home on time.
b1) I may have left my mobile phone on the train.
b2) It's five o'clock; they may have finished by now.
b3) I may have seen something very important.
c1) I might find a job if I'm lucky.
c2) I think they'll get the contract, but they might not.
c3) I might be able to get tickets for the show tonight, it's
just possible !
d1) You're very lucky to be alive; you might have died !
d2) I'm afraid that someone might have heard us.
d3) I might have won if I'd run just a little bit faster.
d4) You might not have broken it if you'd been a bit more
e1) (Please) may I say how happy I am to be here !
e2) Might I ask what you are doing ?
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