Here is some theory and practice!
https://www.englisch-hilfen.de/en/exercises/tenses/simple_present_mix.htm
https://www.ego4u.com/en/cram-up/tests/simple-present-1
http://www.really-learn-english.com/simple-present-exercises.html
https://agendaweb.org/verbs/present_simple-exercises.html
http://www.myenglishpages.com/site_php_files/grammar-exercise-simple-present.php
https://www.perfect-english-grammar.com/present-simple-exercise-7.html