MODAL AUXILIARIES

1.- FORM.     
               can
               will
               could
               must             +   verb
              should
              might
              may
             
               have
               ought         to      verb
EXAMPLES:
Romina will be in class tomorrow.
They can speak English very well.
I have to write an essay.
We ought to see a dentist.
2.-MODALS AND THEIR MEANING
   A) CAN.-    expresses  ability in the present or future.
      COULD   .-  expresses ability in the past.
   B) MAY-MIGHT.- express possibility in the present or future.They have the same meaning.
   C).-COULD.- another meaning for this is possibility in the present or in the future.
   D)MAY I - COULD I - CAN I.- to ask polite questions about permission or agreement.
   E)WOULD YOU -  COULD YOU - WILL YOU -  CAN YOU.-to ask for someone`s help or cooperatrion.
    F)SHOULD -- OUGHT TO.-   express advice
         HAD BETTER   expresses advice and implies a warning about possible bad consequences.
    G)HAVE TO - MUST.- they express the idea that something is necessary (necessity)
    H)DO NOT HAVE TO - MUST NOT.- give the idea that something is NOT necessary.
    I) MUST.- to make logical conclusions.