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

Log onto the following web sites and do the exercises on the present perfect simple and continuous:

http://www.autoenglish.org/gr.percon.i.htm

http://www.englishpage.com/verbpage/presentperfectcontinuous.html

http://www.englishclub.com/grammar/verb-tenses_present-perfect-continuous_quiz.htm

Write any doubts or comments in 'comentarios':