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
  1. HAVE TO/HAVE GOT TO » used for strong obligations not imposed by the speaker
                                                          » used in present and future
  1. 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
  1. 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
                  Â» forma negative ha lo stesso uso di have to
  1. DOESEN’T/DON’T NEED TO
  2. 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