Improve your grammar!

My students ( 10th grade- professional courses) are going to have a test in two days, so they have been asking me to tell them about online exercises so that they can study at home. Here is a possible list.
Try these and more ( the possiblities are endless)

Grammar

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

http://www.ego4u.com/en/cram-up/grammar/simple-past

Present perfect
http://www.englisch-hilfen.de/en/exercises/tenses/simple_past_present_perfect.htm

http://www.ego4u.com/en/cram-up/grammar/present-perfect-simple

Connectors (elementary)
http://www.englishexercises.org/makeagame/viewgame.asp?id=3937

http://www.englishexercises.org/makeagame/viewgame.asp?id=232

Comparatives
http://www.englishexercises.org/makeagame/viewgame.asp?id=2065

Superlatives
http://www.tolearnenglish.com/exercises/exercise-english-2/exercise-english-29600.php

Comparatives versus superlatives

http://www.myenglishpages.com/site_php_files/grammar-exercise-grammar-comparatives-superlatives.php

Reading

 Read about student exchange programs

http://exchangestudentworld.com/student/top-5-reasons-to-become-an-exchange-student/