MODAL VERBS

Use of modal verbs:

-

Must: moral obligation.
Mustn't: moral prohibition.
Can: ability, possibility, or permission.
Can't: inability, impossibility, or no permission.
Have to: external obligation.
Don't have to: it's not necessary.
Should / shouldn't: advice or suggestion

VIDEO
 http://www.youtube.com/watch?v=kZ3rHYcWFlA

PRACTICE

http://www.agendaweb.org/verbs/modals-exercises.html

http://www.learnenglishfeelgood.com/esl-mixed-modals1.html

http://actvenglish.blogspot.com/2012/06/modal-verbs-exercises-can-must-have-to.html

http://www.tolearnenglish.com/exercises/exercise-english-2/exercise-english-87468.php