Placement tests:
learnenglish.britishcouncil.org
Test your Level of English Grammar/Vocabulary on examenglish.com
IH English Language Level Test on ihworld.com
Listening Vocabulary Grammar Reading Level Test on oxfordonlineenglish.com
Grammar Rhymes on youtube collection
GRAMMAR
www.grammarbook.com (on subject verb agreement)
grammar.yourdictionary.com (subject verb agreement)
Коллекция сайтов с упражнениями:
www.perfect-english-grammar.com
www.perfect-english-grammar.com2
engblog.ru, engblog.ru/auxiliary-verbs
englishfull.ru, englishfull.ru
Grammar games:
Коллекция сайтов с объяснениями: