For practicing:
COMPARISON OF ADJECTIVES
https://www.englisch-hilfen.de/en/exercises/adjectives_adverbs/adjective_comparison.htm;
https://www.englisch-hilfen.de/en/exercises/adjectives_adverbs/adjective_comparison3.htm;
https://www.englisch-hilfen.de/en/exercises/adjectives_adverbs/comparative_sentences_2.htm;
https://www.english-4u.de/en/grammar-exercises/comparison-adjectives.htm;
https://www.englisch-hilfen.de/en/exercises/adjectives_adverbs/adjectives_comparison_as_as.htm;
https://elt.oup.com/student/solutions/preint/grammar/grammar_04_012e?cc=lt&selLanguage=en;
https://elt.oup.com/student/solutions/advanced/grammar/grammar_04_012e?cc=lt&selLanguage=en;
https://www.english-4u.de/en/grammar-tests/comparison.htm;
Comparison of Adjectives - Online Quiz
TOO, ENOUGH, REALLY, VERY
https://www.myenglishpages.com/english/grammar-exercise-too-enough.php#google_vignette;
https://www.grammarbank.com/too-or-enough.html;
https://www.tolearnenglish.com/exercises/exercise-english-2/exercise-english-20945.php;
https://www.elt-els.com/2014/09/quantifiers-very-too-enough-multiple.html;
https://www.usingenglish.com/quizzes/239.html;
RELATIVE PRONOUNS
https://www.englisch-hilfen.de/en/exercises/pronouns/relative_pronouns.htm;
https://www.englisch-hilfen.de/en/exercises/pronouns/relative_pronouns2.htm;
https://www.english-4u.de/en/grammar-exercises/relative-pronouns4.htm;
COMPARISON OF ADVERBS
https://www.ego4u.com/en/cram-up/grammar/adjectives-adverbs/adverbs/exercises?02;
https://www.learnenglishfeelgood.com/english-adverbs-comparative1.html;
https://www.englisch-hilfen.de/en/exercises/adjectives_adverbs/adverb_comparison.htm;
