More sites where you can study English Grammar and do gap-fill exercises

English Grammar Online Exercises                                                     
https://www.english-grammar.at/online_exercises/open-cloze/open-cloze-index.htm

ESL Lounge Student

https://mail.google.com/mail/u/0/#inbox/FMfcgxvzMBhFJPZZFlmCNKsMlpfZSsNz