Modals – Part 2 : Offers, Obligation, Necessity, Possiblity and Certainty

After explaining the modals used for Ability, Permission, Requests and Advice expressions in Part1 of Modals lesson. In this  section, We are going to clarify the modals which express :

• Offers and Invitations ( using Can , Shall and Would )

• Obligation and Necessity ( using Must )

• Possibility  ( using Could, Might and May )

• Impossibility ( using Can’t )

• Certainty ( using  Must and should )

Offers and invitations:

• We use can I… and to make offers:

Can I help you?
Can I do that for you?

• We can also use shall I …

Shall I help you with that?
Shall I call you on your mobile?

• We sometime say I can … or I could … or I’ll (I will) … to make an offer:

I can do that for you if you like.
I can give you a lift to the station.
I’ll do that for you if you like.
I’ll give you a lift to the station.

• We use would you like (to) … for invitations:

Would you like to come round to morrow?
Would you like another drink?

• We use you must or we must for a very polite invitation:

You must come round and see us.
We must meet again soon.

Obligation and necessity

• We use must to say that it is necessary to do something:

You must stop at a red light.
Everyone must bring something to eat.
You can wear what you like, but you must look neat and tidy.
I’m sorry, but you mustn’t make a noise in here.

• We use had to for this if we are talking about the past:

Everyone had to bring something to eat.
We could wear what we liked, but we had to look neat and tidy.

Possibility:

• We use the modals could, might and may to show that something is possible in the future, but not certain:

They might come later. (= Perhaps/Maybe they will come later.)
They may come by car. (= Perhaps/Maybe they will come by car.)
If we don’t hurry we could be late. (= Perhaps/Maybe we will be late)

• We use could have, might have and may have to show that something was possible now or at some time in the past:

It’s ten o’clock. They might have arrived now.
They could have arrived hours ago.

• We use the modal can to make general statements about what is possible:

It can be very cold in winter. (= It is sometimes very cold in winter)
You can easily lose your way in the dark. (= People often lose their way in the dark)

• We use the modal could as the past tense of can:

It could be very cold in winter. (= Sometimes it was very cold in winter.)
You could lose your way in the dark. (= People often lost their way in the dark)

Impossibility:

• We use the negative can’t or cannot to show that something is impossible:

That can’t be true.
You cannot be serious.

• We use couldn’t/could not to talk about the past:

We knew it could not be true.
He was obviously joking. He could not be serious.

Certainty ( Making Deductions) :

• We use the modal must to show we are sure something to be true and we have reasons for our belief:

It’s getting dark. It must be quite late.
You haven’t eaten all day. You must be hungry.

• We use must have for the past:

They hadn’t eaten all day. They must have been hungry.
You look happy. You must have heard the good news.

• We use the modal should to suggest that something is true or will be true in the future, and to show you have reasons for your suggestion:

Ask Miranda. She should know.
It’s nearly six o’clock. They should arrive soon.

• We use should have to talk about the past:

It’s nearly eleven o’clock. They should have arrived by now.

To go to 

PART 1

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