2. Obligation and necessity:
must, have to
We use must when the authority comes from
the speaker
You must be home by 10 o’clock
I’ve got a pain in my back. I must go
and see the doctor.
We use have to when the authority comes
from outside the speaker
I have to be home by 10 o’clock. (My
parents insist)
3. Obligation and necessity:
must, have to
• Must: for present and future (the rest of
tenses with have to
I had to work late yesterday
I must work late tomorrow
He hates having to get up early
She’s had to work hard all her life
Did you have to walk home last night?
4. Obligation and necessity:
must, have to
Use must and: drink, take, stay and
continue
Doctor: Well,Mrs. Woods, your
temperature is a little
high, so you … in bed. You
can eat whatever you like,
but you …plenty of liquids.
And I’ll give you some
medicine. You …it three
times a day after meals.
And you …to take it for
the next ten days.
5. Obligation and necessity:
must, have to
• Use: have to and drink take and continue.
• Mrs Woods: The doctor gave me some
medicine. …it three times a day after
meals. And I …to take it for the next ten
days. I’m not allowed to get up at the
moment. I …in bed for the next few days.
Oh, and I’m allowed to eat whatever I like,
but I …plenty of liquids.
6. Obligation and necessity:
mustn’t, don’t have to, don’t
need to
• We use mustn’t
when there is an
obligation not to
do something
• We use don’t have
to when it is not
necessary to do
something. We can
also use don’t need
to, or needn’t
7.
8. Possibility: may, might,
could
-to talk about present or future possibility.
+++may ++might +could
“There’s someone at the door”. It may be
Sarah. (=Perhaps it is Sarah)
“We aren’t sure what we are going to do
tomorrow. We might go to the beach.
(Perhaps we will go to the beach)
“Where’s Simon?” “He could be in the living
room”. (Perhaps he is in the living room)
9. Obligation and advice:
should, ought to
• to talk about obligation and duty, to ask for and
give advice, and, in general, to say what is right or
good.
• You should learn to swim/You ought to learn to
swim
• You shouldn’t tell lies/You oughtn’t to tell lies
• Ought to: to talk about authority which comes
from outside the speaker (laws, rules)
• Should +inf without to
• Ought to +inf
http://www.youtube.com/watch?
v=GqH21LEmfbQ
