Page 75 - English Grammar - 8

Permission—Can, Could, May

The modals can, could, and may are used:
 to ask for something in an informal way. For example:

Can I get those sandwiches?
O
Can I go home now?
O
 to ask for something in a formal and a polite way. For example:
Could I ask a question, please?
O
May I come in?
O
 to grant permission in an informal way. For example:
You can go home now.
O
You can borrow my jacket.
O
 to grant permission in a formal and a polite way. For example:
You may go home now.
O
You may borrow my jacket.
O
Ability—Can, Could

The modals can and could are used:
 to talk about a person’s abilities or skills. For example:

He can swim like a fish.
O
She can’t sing well.
O
 to talk about the skills or abilities of a person in the past. For example:

By the time she was 12, she could speak three languages fluently.
O
The burglar couldn’t get in through the window.
O

Obligation—Must, Should

The modals must and should are used:
 for a strong obligation, which means it is necessary to do. For example:
I must return home by dusk.
O
Students must arrive on time.
O
 for a mild obligation, which is more like an advice. For example:

You should visit them in their hour of need.
O
You should have saved some money.
O

Suggestion and Advice—Should, Ought to, Must, Have to, Had better Modals
The modals should, ought to, must, have to, and had better are used to offer suggestions
and advice. For example:
You should try to strike a balance between emotion and practicality.
O
You ought to show your report card to your parents.
O
You must not drive across the desert after dark.
O
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