Other interesting links where you can find exercises to practice the Present Simple are the next:
http://www.isabelperez.com/happy/tenses/present_simple.htm
http://www.isabelperez.com/pr-simple.htm
http://www.isabelperez.com/pr-simple-neg.htm
http://www.isabelperez.com/q1.htm
http://www.isabelperez.com/q-a-easy.htm
In this web you have a large amount of activities:
http://www.agendaweb.org/verb/present_simple.html
