Sj + verb to be (AM/IS/ARE) + -ing of a verb + Complement.
POSITIVE FORM
- http://www.eclecticenglish.com/grammar/PresentContinuous1B.html
- http://www.isabelperez.com/happy/tenses/exercises/present_cont_1.htm
- http://www.ego4u.com/en/cram-up/grammar/present-progressive/form/exercises?form02
- http://web2.uvcs.uvic.ca/elc/studyzone/330/grammar/pcont1.htm
NEGATIVE FORM
- http://www.eclecticenglish.com/grammar/PresentContinuous1C.html
- http://www.ego4u.com/en/cram-up/grammar/present-progressive/form/exercises?form03
YES/NO- QUESTIONS
- http://www.eclecticenglish.com/grammar/PresentContinuous1D.html
- http://www.ego4u.com/en/cram-up/grammar/present-progressive/form/exercises?form04
WH- QUESTIONS
- http://www.eclecticenglish.com/grammar/PresentContinuous1E.html
- http://www.ego4u.com/en/cram-up/grammar/present-progressive/form/exercises?form05
MIXED
- http://www.eclecticenglish.com/grammar/PresentContinuous1F.html
- http://www.isabelperez.com/happy/tenses/exercises/pres_cont_quest1.htm
ADD -ING
- http://www.isabelperez.com/happy/tenses/exercises/present_cont_2.htm
- http://www.eclecticenglish.com/grammar/PresentContinuous1F.html
TEST