Form 6a. Revision on grammar of units 11 - 12

For practicing:
https://www.ego4u.com/en/cram-up/grammar/adjectives-adverbs/adjectives/exercises;
https://www.perfect-english-grammar.com/comparative-adjectives-exercise-1.html;
https://www.tolearnenglish.com/exercises/exercise-english-2/exercise-english-118322.php;
https://anthonyhalderman.com/english/compsup.htm;
http://esl.fis.edu/grammar/multi/adadv.htm;
https://www.usingenglish.com/quizzes/33.html;
https://www.englisch-hilfen.de/en/exercises/adjectives_adverbs/adjective_adverb.htm;
https://www.proprofs.com/quiz-school/story.php?title=conjunctions--but-so-1;
http://a4esl.org/q/h/vm/m-sco01.html.