1.  Unit 6: Grammar section.
Modal verbs
 Unit 6: Grammar section.

2. Three basic rules Except Invariable verbs: -s
No auxiliaries: do / does
Always followed by INFINITIVE
Be able to + INF
Have to + INF
Need to + INF
Except

3. Ability Present: Can / can’t + INF Ex: Jim can draw very well. Future:
Will / won’t + be able to + INF
Ex: When I finish my project I will be able to go out with my friends.

4. Ability Past: [Particular past ability: “poder”]
Was / wasn’t or were / weren’t able to + INF
[Particular past ability: “poder”]
Ex: The boat sank near the beach, so we were able to swim to the shore.
Could / couldn’t + INF
[General past ability: “saber”]
Ex: We could swim when we were 5.

5. Obligation Necessity / Obligation: Must + INF [Strong / personal]
Ex: You must wear a helmet when you ride a bike.
Have to + INF [Task]
Ex: I have to do my homework before dinner.
Need to + INF [Necessity]
Ex: I need to go to the bank.

6. Obligation Lack of Obligation: Don’t / doesn’t have to + INF
Ex: You don’t have to sweep the floor, there is someone to do it for you.
Needn’t + INF
Ex: You needn’t bring anything to the dinner.

7. BUT Be careful! Need is followed by to + INF in affirmative forms:
Ex. I need to go to the bank.
The negative form, Needn’t , is only followed by the INF:
Ex. You needn’t use your car.
BUT

8. Obligation Prohibition: Mustn’t + INF
Ex: Students mustn’t run in the corridors.
Can’t + INF
Ex: You can’t use the computer after midnight.

9. advice Affirmative: Should / Ought to + INF
Ex: You should / ought to stop eating chocolate if you want to lose weight.
Negative:
Shouldn’t + INF
Ex: You shouldn’t eat so much chocolate if you want to lose weight.

10. Certainty Sure: Must + INF [I am sure that…]
Ex: She must be happy because she has won the car.
Impossible: [It’s impossible that…]
Can’t + INF
Ex: She can’t be at class because she is abroad.

11. Certainty Possible: May + INF [Stronger]
Ex: It may be quicker to travel by train.
Might + INF
Ex: We might get lost if we don’t use a map.

12. Certainty Possibility can also be expressed using: Can + INF
Ex: We can paint the walls later.
Be able to + INF
Ex: I think they will be able to win this time.
Could + INF [Remote possibility]
Ex: We could go on Friday evening.

13. request Formal: May + INF [Very formal] Could + INF Would + INF
Ex: May I use your phone, please?
Could + INF
Ex: Could you tell me the way to the station?
Would + INF
Ex: Would you like to help me with the luggage?
Informal:
Can + INF
Ex: Can you speak more clearly?

14. Suggestion & offer Suggestion: Could + INF [Formal]
Ex: You could join our team next week.
Can + INF [Informal]
Ex: You can sing that song again!
Offer:
Would+ INF
Ex: Would you like a cup of tea?

15. PERFECT Modal verbs
Actions in the past.
Modal + have + participle

16. Certainty Sure: Must + HAVE + PARTICIPLE
[A certainty or logical conclusion about an event in the past]
Ex: The lights are out. Everyone must have left .
Impossible:
Couldn’t + HAVE + PARTICIPLE
[A certainty that something did not happen]
Ex: She couldn’t have done a better job.

17. Certainty Possible: May / Might + HAVE + PARTICIPLE
[A guess about something that happened in the past. You’re not sure of it]
Ex: She may / might have read this book, but I’m not sure.

18. Ability Only in affirmative: Could + HAVE + PARTICIPLE
[The ability to do something in the past, but which in the end was not done]
Ex: You could have avoided that accident.

19. Criticism or regret In affirmative:
Should / Ought to + HAVE + PARTICIPLE
[Advice which was not followed in the past]
Ex: You should /ought to have listened to me.
[Expectations which were not fulfilled]
Ex: They should / ought to have nominated the film for an Oscar.
In negative:
Shouldn’t + HAVE + PARTICIPLE
[Criticism that is given after an event]
Ex: He shouldn’t have refused the opportunity.

20. Desire Would + HAVE + PARTICIPLE
[Desire to do something in the past which in fact could not be done]
Ex: I would have lend you my car but my father needed it too.

21. Unnecessary action Needn’t + HAVE + PARTICIPLE
[Something that was done but it was not necessary]
Ex: You needn’t have raised your voice.