Write the correct form of can or may in the spaces provided.
1. Can expresses present ability, and no "-s" or "-es" is added to the third person singular. In the past, we use
could.
She can drive a lorry. (= She knows how to drive a lorry.)
They could swim like a fish when they were kids. (= They knew how to swim like a fish when they were kids.)
As for the rest of verb tenses,
be able to is necessary because
can is a defective verb
, that is, it does not have all the forms.
I have been able to drive since I was eighteen (years old). (present perfect)
She will be able to lend you a hand when she comes. (future simple)
In the negative, we use
can't (contracted form) or
cannot (full form). In the interrogative, we place
can before the subject.
He can't/cannot play the guitar.
Can he play the guitar?
As regards
could, the negative is
could not. In the interrogative, we put
could before the subject.
She could not/couldn't play chess as a girl.
Could she play chess as a girl?
a They __________ (not) sing at all, so they will not __________ sing in the school choir.
b I __________ learn languages very easily when I was at school.
c "__________ you speak French?"
"I __________ speak it as a child, but I _____(not) now."
d We will not __________ help you if you don't tell us the truth.
e She hasn't __________ speak since her accident.
2. Could is only possible for general ability in the past, in the negative, or with perception verbs such as "see" or "hear". When we are referring to a particular situation,
was/were able to must be used.
As a child, I could run and jump all day without getting tired. (general ability)
When she entered the house, she could smell gas. ("Smell" is a perception verb)
I lost my wallet in the street, but I was able to find. (particular situation)
I lost my wallet in the street, but I couldn't find it. (negative)
a As she entered her room, she __________ perceive an unpleasant odour. Her dog had done its business on the carpet.
b Almost everybody failed the exam, but my son __________ pass it.
c He __________ (not) do anything to save them: they had already drowned when he got there.
d When I was at university, I __________ spend a lot of time reading, but now I can't.
e Last year, he __________ break the world record for javeling throwing.
3. To ask for permission, use
can (or more formally
could or
may); to give it,
can or
may (formal). Have a look at the following examples:
"Can/Could/May I go to the loo?" (= Do you let me go to the loo?)
"Yes, of course!"
You can/may go to the cinema with your friend, but don't come home late. (= I let you go to the cinema with your friend, but don't come home late.)
As both
can and
may are defective verbs, we have to use
be allowed to when
can or
may are impossible. Let's see a few examples:
We have been allowed to use this swimming-pool since we moved into this house.
She used to be allowed to arrive home after midnight.
From next week on, you will not be allowed to smoke/you can't smoke in your bedrooms.
He could/was allowed to stay up until midnight when he was twelve.
a "__________ I sit down?"
"Yes, please do."
b You've been a good boy, so you __________ telly tonight.
c We haven't __________ park in this street since last year.
d She __________ do what she wanted when she was living with her grandparents.
e "__________ I go with you, daddy?"
"Yes, sweetheart!"
4. May also expresses present or future possibility. It means "it is possible (that)" or "perhaps":
We may visit her this afternoon. (= It it possible that we visit her this afternoon.)
The negative is
may not. Avoid "mayn't".
She may not come tomorrow. (= It it possible she does not come tomorrow.)
In the interrogative, use
do you think...?:
Do you think (that) she will come tomorrow?
When we refer to a general possibility, we use
can; in the past,
could:
The sea can often be dangerous.
When she was a child, she could be very naughty at times.
Could and
might indicate a smaller possibility than
may:
She could/might do it. (I do not think she will do it, but who know?)
a We __________ go swimming this afternoon. If so, would you like to come?
b "He hasn't studied at all."
"Well, still, he __________ pass."
"If you say so!"
c The bite of this snake __________ often be fatal.
d "I __________ (not) tell them. I don't know what to do. Shall I tell them?"
"Well, this is up to you!"
e "__________ it will rain this afternoon?"
"I really don't know!"
5. Please note that
a modal verb + have + a past participle refers to the past:
She may/might have had an accident. (Perhaps she had an accident.)
You could have told me that he was not going to come! (Why didn't you tell me?)
She can't/couldn't have done such a thing.(It is impossible for her to have done such a thing.)
a "The Smiths were coming to the barbecue, but haven't arrived yet, and it's getting very late."
"They __________ have forgotten to come."
"I don't think so. They love barbecues. They __________ have had a puncture."
"A puncture _____(not) have delayed them so much!"
"Let's phone them to see what has happened to them."
"OK!"
b You __________ have told me that the exam was postponed. I spent all night long studying!
c They __________ (not) have talked to him last night: he's abroad!
d He __________ (not) have bought a Rolls-Royce. He's as poor as a church mouse.
e You __________ have taken a taxi! Why didn't you take a taxi?
6. Revision exercise.
a "__________ you dance a walts?"
"No, I'm afraid I _____(not)."
b That year I __________ get the gold medal. It was the happiest day of my life.
c We __________ tour the world next summer, but still don't know for sure.
d Sometimes he __________ be very sweet, but he used to be very strict.
e That place __________ be very dangerous. So I don't want you to go there again.
f He __________ fail, but I think he'll pass.
g You __________ (not) pick your nose in front of everybody. It's not appropriate for a young lady.
h "__________ they'll let you down?"
"No, I don't think so."
i They __________ (not) have read the book, or they would know the plot.
j "I __________ play draughts very well. Shall we have a game now?"
"I'm very sorry, but I _____(not) play draughts. What about a game of cards, instead?"
k "__________ I go to tonight's concert, daddy?"
"Yes, you __________ as long as you don't get home very late."
l I __________ see that something fishy was going on, so I decided to leave at once.
m She used to __________ cheer us up in no time at all. We miss her a lot.
n "__________ I speak, sir?"
"Yes, go ahead."
o I'm afraid to tell you that Mr Turner won't __________ attend the meeting. He's got a terrible cold.
p Well, they __________ help you, but this is very unlikely.
q He hasn't __________ see her since she was in hospital. He's been very busy lately.
r We had better
stay here, as it __________ rain this afternoon.
s There __________ be another strike next week, so we'd better cancel our flight.
t You __________ stay here as long as you don't interfere.
u "__________ I help you, madam?"
"Yes, I'm looking for a yellow pair of shoes."
v He __________ be very ugly, but he's so sweet and intelligent. I'm in love with him.
w When I was at school, I __________ do square roots very easily, but I _____(not) now.
x You _____(not) do that. It's very impolite.
y You _____(not) take a day off. We have a lot of work at the office these days.
z You __________ have waited for me. I'm very cross that you didn't.
____________________
Click here for further information about defective verbs.
Was/were able to is also possible here, but less usual.
As a child, I was able to run and jump all day without getting tired.
Was/were allowed to must be used to refer to a particular situation, as stated in section
2 above.
He was allowed to stay up all night yersterday, as it was Christmas Eve.
Compare this sentence with the following one:
She can't come tomorrow. (ie, it is impossible for her to come tomorrow.)
See also
Unit 4, section 7.
The meaning of
had better is close to the one expressed by "should".