2. General Characteristics:
1- They have no infinitives, past participles or -ing forms, and other
expressions are used instead.
For example we use “be able to” instead of can and “have to”
instead of must.
Compare these examples:
- Mary can speak English very well.
- You will be able to drive a car when you are 18. (infin.)
- I have never been able to understand my son. (past part.)
- I love being able to get up late on Sundays. (-ing forms)
- We must study hard for our exams.
- You will have to study harder when you go to university. (inf.)
- We have had to call the doctor because she doesn’t feel well. (past
part.)
- Having to get up early every day is quite stressful. (- ing form)
3. 2- Modal verbs have no -s on the third person singular.
- She can play the piano.
- He may come tomorrow.
3- Questions and negatives are made without “do”
- Can your mother drive?
- Should I dress up to go to the party?
- You shouldn’t speak like that
- You cannot smoke at school
4- They are followed by the infinitive without to of other
verbs (except “ought to”)
- She could be in Paris or London or Tokyo - nobody
knows
but - You ought to stop worrying about your weight.
4. EXPRESSING ABILITY: CAN,
COULD, BE ABLE TO
CAN expresses ability to do something.
(saber)
She can skate very well but she can’t swim
(= She knows how to skate but she
doesn’t know how to swim)
Notice this:
*You will be able to speak English fluently
when you go to England.
*Being able to speak several languages is
amazing.
5. COULD.
A) General ability in the past. (sabía)
- My grandfather could speak five languages.
- When Tom was 16, he could run 100 metres in 11
seconds.
But if we refer to a particular situation, we have to use
was/were able to (pudo...)
- The fire spread through the building very quickly but
everyone was able to escape.
- They didn’t want to come with us at first but in the end we
were able to persuade them.
Compare could - be able to:
- Jack was an excellent player. He could beat anybody but
once he had a difficult game against Alf. Alf played very well
but in the end Jack was able to him.
6. Couldn’t is possible in all situations (general
or particular):
- We tried hard but we couldn’t persuade
them to come with us.
- My grandfather couldn’t swim.
Could is used with verbs like “see, hear,
smell”
- Although they were whispering, I could
hear what they said.
7. POSSIBILITY AND DEDUCTION
CAN: General possibility. (poder)
- It can be cold in Granada in winter.
- Anybody can make a mistake.
- You can swim because there is an indoor swimming-pool
in our town.
MAY: Present of future possibility.
- I may go to aerobics class. (puede que)
- He may start a diet tomorrow.
MIGHT/ COULD: Remote possibility in the present or
future. (pudiera ser que)
- She might win the race, but she hasn’t trained hard
enough.
- Are you sure about it?, You could be wrong.
- Look at the sky. It could rain this afternoon.
8. POSSIBILITY IN THE PAST:
May/ might/could have+ past part.
A guess about a past action. We do not know what
actually happened.
Paul is late for work. He may have missed the
bus, he might have overslept or he could have
had an accident.
When you had the ability or possibility of doing
something in the past; but you didn’t do it.
I could have gone to the party but I didn’t want to
9. LOGICAL DEDUCTION: MUST /
CAN’T
The lights are on. She must be at home.
(affirmative)
The lights are off. She can’t be at home
(negative)
In the past…
Paul didn’t answer my calls. He must have
been out all day.
John can’t have studied hard. He failed the
exam
10. OBLIGATION/ADVICE/NECESSITY
MUST/ HAVE TO
Must expresses “moral obligation” (strong obligation)
- I must write to Ann, I haven’t written to her for ages. (The speaker thinks it’s
necessary. It’s his/her moral obligation)
Compare it with “have to”:
- I have to wear a uniform in my school (it means external obligation)
In the second person: Must expresses speaker’s authority:
- Doctor: You must cut down on your smoking.
- Mother: You must wear a dress tonight. You can’t go to the opera in those
dreadful jeans.
If you are talking to a friend you usually use “have to”:
- It’s already 12 o’clock. Be careful, you have to be back home early.
Have a look at some more examples:
- The government really must do something about unemployment. (The speaker
personally feels that the government must do something)
With “have to” the speaker is not giving his own feelings. He is just giving facts.
- Ann’s eyes are not very good. She has to wear glasses.
* For the past, future, past participle and inf, we have to use “have to”
- There were no buses so she had to walk
11. ADVICE:
We use SHOULD to give advice
- You should eat more fresh fruit.
- You shouldn’t waste so much time watching TV
- Should we talk to him?
OUGHT TO is quite similar to should, but less frequently
used.
- You ought to come more frequently.
HAD BETTER: in a specific situation. You suggest there
will be a problem if something is not done.
I have a terrible headache.
- You’d better go home.
-You’d better not cry, you’d better not pout. Santa Claus is
coming to town.
12. Notice the difference:
-It rained all the time and I didn’t take my umbrella. I
should have taken my umbrella.
(it was the right thing to do but you didn’t do it)
-It didn’t rain at all, but I took my umbrella.
I needn’t have taken my umbrella.
(you did something which wasn’t necessary)
- I spent my holidays in sunny Spain so I didn’t
need to take my umbrella.(=didn’t have to)
(it wasn’t necessary/ absence of obligation)
- I spent my holiday in rainy England so I had to
take my umbrella.
(obligation in the past)
