Must and Have to
- Students must come to school at 9 o'clock.
- This must be the new pupil, I don't know him.
- You must do something to improve your english.
- They have to come to the school on time. They are always late.
- I have to go to the doctor, I hurt my knee.
NO OBLIGATION
Don't have to/ Don't need to/ needn't
- You don't have to come, there are enought of us.
- We needn't go to help them, they have hired a removal company.
- She doesn't need to bring money. Everything is paid by the school.
NECESSITY
Need to
- We need to agree on this point before starting.
- Everybody needs to be happy once a day.
- They need to know the train timetable to plan the trip.
PROHIBITION
Musn't
- Remember for our trip:
- We mustn't carry scissors in our hand luggage.
- We mustn't go in to the cathedral with shorts.
- We mustn't take pictures in this museum.
- We mustn't go out alone, we can get lost.
- We mustnt't drink tap water.
ADVISE
Should/Ought to/ Had better
- You should know by now which book to bring to the class.
- We should read the newspaper sometimes. There are good offers.
- She ought to buy a ticket soon if she wants to go to the concert.
- If you can't see well the blackboard, you had better visit the oculist.
- The bus is here. I had better to get on now.
ABILITY and KNOWLEDGE
Can/ Could/ Be able to
- We can do a very nice project today.
- Pablo can do a big drawing and the others can paint it,
- We couldn't finish the mural last week,
- If everybody works, we will be able to finish it this week.
PERMISSION
Can/ Could/ May
- Can I sit in this chair?
- Sorry, I'm late. May I come in?
- May I go to school with you tomorrow?
- You may always come with us.
- Could I borrow your book, please?
SPECULATION, DEDUCTION and PROBABILITY
May/ Might/ Could
- Are you coming on the excursion? I don't know, I may go
- Do you know what the weather will be like on saturday? No, it might rain
- or it might be sunny. I don't trust the weather forecast. When they say it's going to be cloudy
- it could be anything.
- Anyway we could take our raincoats.
May/ might not or Mightn't/ Could not or Couldn't
- We are driving to the airport, but we may not arrive on time.
- We couldn't arrive on time, there was a crash accident in the road.
- I am in the third year of the degree course and I might not finish it in june.
Must/ Can't
- Your jacket must be in the playground I saw you with it on.
- It can't be far from here, you were wearing it this morning.
- We must study hard for the exam,
- It can't be so difficult, we passed the other one.
REQUEST, OFFERS and SUGGESTIONS
Can/ Could/ Would/Shall
- Can you lend me your English book?
- Could you mind if I writer the answer in your book?
- Would you like to play in our team?
- Shall I show you the way?