http://www.english-4u.de/pres_prog_ex1.htm
http://www.english-4u.de/pres_prog_ex2.htm
http://www.ego4u.com/en/cram-up/grammar/present-progressive/form/exercises?form02
http://www.englishclub.com/grammar/verb-tenses_present-continuous_quiz.htm
http://www.isabelperez.com/happy/tenses/exercises/present_cont_1.htm
http://www.ego4u.com/en/cram-up/grammar/present-progressive/form/exercises
http://www.ego4u.com/en/cram-up/grammar/present-progressive/form/exercises?form03
http://www.ego4u.com/en/cram-up/grammar/present-progressive/form/exercises?form04
http://www.ego4u.com/en/cram-up/grammar/present-progressive/form/exercises?form05