E.S.O.: Past simple/ past continuous/ present perfect

Log onto the following web pages and do the exercises on the past simple, past continuous and present perfect:

http://www.isabelperez.com/happy/tenses/past_cont.htm

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

http://www.ego4u.com/en/cram-up/grammar/simpas-paspro/exercises?ex02

http://www.englishpage.com/verbpage/verbs5.htm

http://www.englishpage.com/verbpage/verbs6.htm

http://www.nonstopenglish.com/exercise.asp?exid=912

Write any doubts or comments you have in 'comentarios'.