Object pronoun exercises

https://www.learnclick.com/mchoice/show/851
http://www.englisch-hilfen.de/en/exercises/pronouns/personal_pronouns3.htm
http://a4esl.org/q/h/9901/jd-pronouns.html
http://www.myenglishpages.com/site_php_files/grammar-exercise-object-pronouns.php