U11 - Tenses - mix
http://www.helpforenglish.cz/article/2014082903-cviceni-minuly-cas-prosty-prubehovy
http://www.helpforenglish.cz/article/2014082903-cviceni-minuly-cas-prosty-prubehovy
http://www.helpforenglish.cz/article/2007091802-minuly-a-predminuly-cas-2
http://www.ego4u.com/en/cram-up/grammar/past-perfect-simple/exercises
http://www.englisch-hilfen.de/en/exercises/tenses/simple_past_progressive2.htm
http://www.englisch-hilfen.de/en/exercises/tenses/simple_present_progressive3.htm