1. CAN and COULD
2. MAY and MIGHT
3. WILL and WOULD
5. HAD BETTER
We use can:
a) to talk about possibility and ability;
EXAMPLE: I can ride a horse.
EXAMPLE: He can speak three languages.
b) to make requests or give orders;
EXAMPLE: Can you buy me a can of beer?
EXAMPLE: Can you complete now what you are doing?
We use could:
a) as the past tense of can.
EXAMPLE: Jane said she could get the tickets for us.
b) when we wish to be very polite.
EXAMPLE: Could I go now, please?
c) to show what was possible in the past.
EXAMPLE: He could cycle when he was four years old.
We use may or might to:
a) make a suggestion or an assumption.
EXAMPLE: Everyone is looking for George. He may/might be in the toilet.
b) indicate that something is a possibility.
EXAMPLE: What we are told may/might be true.
c) possibly take the place of could.
EXAMPLE: That man over there looks like Mike. He could/may/might be Mike.
We use will and would :
a) for polite questions.
EXAMPLE: Will/would you phone me later?
b) for invitations
EXAMPLE: Will/would join us for a drink?
c) for offering something
EXAMPLE: Would/wouldn’t you like a coffee or tea?
d) for asking someone to do something
EXAMPLE: Will/would you please top grumbling about the weather?
a) We usually use had better to give advice or warning or make a suggestion about something bad that is likely to happen.
EXAMPLE: You are coughing loudly. You had better see a doctor.
EXAMPLE: I am overeating. I had better go on a diet.
EXAMPLE: We think she had better not befriend him. He is a drug addict.