Have you done it? or Did you do it? (Present Perfect or Simple Past)

http://www.ego4u.com/en/cram-up/grammar/simpas-preper

http://web2.uvcs.uvic.ca/elc/studyzone/410/grammar/ppvpast1.htm

http://www.leshoekje.be/leshoekje/ICT-oef%20ENG2/present-past3.htm

http://www.englisch-hilfen.de/en/exercises/tenses/simple_past_present_perfect.htm