For Grammar:
https://www.khanacademy.org/humanities/grammar
http://www.quickanddirtytips.com/grammar-girl
https://owl.english.purdue.edu/owl/section/1/5/
http://www.shmoop.com/grammar/​
http://grammarist.com/​
http://www.chompchomp.com/menu.htm​
For MLA:
https://owl.english.purdue.edu/owl/resource/747/01/
http://www.easybib.com/
For Vocabulary:
Vocabularyworkshop.com
yourdictionary.com

For Reading:
http://www.sparknotes.com/
http://www.shmoop.com/