MODAL VERBS - unità 3

OBLIGATION, NECESSITY, PERMISSION

STRONG OBLIGATIONS

1. MUST » used for strong obligations imposed by the speaker

                        » used to talk about laws and regulations

                        » used in present and future

2. HAVE TO/HAVE GOT TO » used for strong obligations not imposed by the speaker

                                                          » used in present and future

3. HAD TO » used in past

                      » used with reported obligations

WEAK OBLIGATIONS

1. SHOULD » used in present (should have done used in the past)

                        » should + present tense

                        » there isn’t difference between should and ought to

                        » used to give advices, to say that is good or bad to do something

2. OUGHT TO » used in present (ought to have done used in the past)

                           » ought + to + infinite

                           » the past form (for both two) is used for criticism or regret because an action  

                              didn’t happen

LACK OF OBLIGATIONS

1. NEED » used to talk about something that is urgent or necessary

                  » forma negative ha lo stesso uso di have to

2. DOESEN’T/DON’T NEED TO
3. DOESEN’T/DON’T HAVE TO

ASKING/GIVING FOR PERMISSION

1. CAN » used to giving/asking permission
2. COULD » more polite
3. MAY » formal
4. OTHER WAYS » to allow someone to do

                                 » to permit someone to do

                                 » to let someone to do