PRESENT SIMPLE vs PAST SIMPLE

Activities:

http://www.saberingles.com.ar/curso/lesson15/06.html

http://www.tolearnenglish.com/exercises/exercise-english-2/exercise-english-87374.php

Past Simple:

http://www.myenglishpages.com/site_php_files/grammar-exercise-simple-past.php#.VMypBig0fIY

Present Simple Negative:

http://www.english-4u.de/pres_neg_ex1.htm

Present Simple Questions:

http://www.english-4u.de/present_ques_ex1.htm