http://www.usingenglish.com/quizzes/326.html
http://www.usingenglish.com/quizzes/115.html
http://www.myenglishpages.com/site_php_files/grammar-exercise-used-to.php
http://www.englishexercises.org/makeagame/viewgame.asp?id=5988
http://esldivlabs.vcc.ca/ELSA/Instructor_Web_Exercises/Grammar/Used_to_Cloze.htm
http://speakspeak.com/english-grammar-exercises/intermediate/used-to-be-used-to-get-used-to