- a) countables – uncountables
explanation:
https://learnenglish.britishcouncil.org/grammar/english-grammar-reference/uncount-nouns
exercises:
https://www.englisch-hilfen.de/en/exercises/nouns_articles/countables.htm
https://www.englisch-hilfen.de/en/exercises/nouns_articles/singular_plural3.htm
https://englishlessonsbrighton.co.uk/countable-uncountable-nouns-plurals-exercises/
https://english.lingolia.com/en/grammar/nouns/countable-uncountable/exercises
- b) pair words
explanation:
http://masteringarticles.com/pair-nouns/
- c) mixed exercises
https://www.esl-lounge.com/student/grammar/3g28-news-is-are.php
https://webapps.towson.edu/ows/SelfTeachingUnits/SubjectVerbAgreementExercise4.aspx
https://www.englisch-hilfen.de/en/exercises_list/passiv.htm