Grammar exercises

These are some useful links to practise grammar. Again, write in your diary saying how easy/difficult/helpful... you found them.

Prepositions:
http://a4esl.org/q/j/ni/fb-prepositions.html
http://a4esl.org/q/h/9704/dg-in-at-on.html
Questions:
http://a4esl.org/q/h/9704/dg-wh.html
Present perfect:
http://www.ego4u.com/en/cram-up/grammar/simpas-preper
Future:
http://www.ego4u.com/en/cram-up/grammar/future-mix