Mixed tenses

See the overview of tenses here:

http://www.englisch-hilfen.de/en/grammar/tenses_table.pdf

Practise tenses here:

http://www.englisch-hilfen.de/en/exercises_list/zeitformen.htm

You can download this file to practise as well:

http://uloz.to/xMBGKxxC/mixed-verb-tenses-doc