SIMPLE PRESENT TENSE

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

http://www.agendaweb.org/verbs/present-simple-elementary-level-exercises.html

http://www.agendaweb.org/verbs/present-simple-negative.html

http://www.agendaweb.org/verbs/present-simple-interrogative-exercises.html

http://www.agendaweb.org/verbs/present-simple.html

http://isabelperez.com/grammar.htm