http://moviesegmentstoassessgrammargoals.blogspot.com.es/2010/07/hunger-since-x-for-present-perfect.html

http://moviesegmentstoassessgrammargoals.blogspot.com.es/2010/12/paranormal-activity-since-x-for.html

http://www.englisch-hilfen.de/en/exercises/tenses/present_perfect_mix2.htm