ПРАВИЛО ПО ССЫЛКЕ: http://usefulenglish.ru/grammar/subject-verb-agreement
УПРАЖНЕНИЯ И ТЕСТЫ:
http://grammar.ccc.commnet.edu/grammar/quizzes/svagr2.htm
http://www.grammarbook.com/grammar_quiz/subject_verb_agreement_1.asp
http://www.mhhe.com/socscience/english/langan/sentence_skills/exercises/ch09/p4exe.htm
http://www.eflnet.com/grammar/subverb.php
http://businesswriting.com/tests/subjectverb.htm
https://www.espressoenglish.net/advanced-subject-verb-agreement-exercises/
УПРАЖНЕНИЯ И ТЕСТЫ:
http://grammar.ccc.commnet.edu/grammar/quizzes/svagr2.htm
http://www.grammarbook.com/grammar_quiz/subject_verb_agreement_1.asp
http://www.mhhe.com/socscience/english/langan/sentence_skills/exercises/ch09/p4exe.htm
http://www.eflnet.com/grammar/subverb.php
http://businesswriting.com/tests/subjectverb.htm
https://www.espressoenglish.net/advanced-subject-verb-agreement-exercises/