This two
topics are difficult to me and those links it is a perfect level to improve and
understand perfectly the grammar:
Have to and don't have to (use)
This exercises
help me to understand have to use in different situations and with some
examples to do more easily understand.
http://www.eclecticenglish.com/grammar/HaveTo1A.html
Future forms:
This quiz
is perfect to practice future forms and all its forms completing sentences.
http://esl.about.com/library/quiz/blgrquiz_future.htm