1) https://www.ego4u.com/en/cram-up/vocabulary/much-many/exercises
2) https://www.ego4u.com/en/cram-up/vocabulary/much-many/exercises?02
3) https://www.ego4u.com/en/cram-up/vocabulary/much-many/exercises?04
4) http://www.englisch-hilfen.de/en/exercises/confusing_words/much_many3.htm
