http://www.englisch-hilfen.de/en/exercises/adjectives_adverbs/adjective_comparison.htm
http://www.english-4u.de/comparison_ex4.htm
http://www.englisch-hilfen.de/en/exercises/adjectives_adverbs/adjective_comparison2.htm
http://www.englisch-hilfen.de/en/exercises/adjectives_adverbs/adjective_comparison3.htm
http://www.english-4u.de/comparison_ex1.htm
http://www.english-4u.de/comparison_ex2.htm
http://www.ego4u.com/en/cram-up/grammar/adjectives-adverbs/adjectives/exercises
http://www.englishexercises.org/makeagame/viewgame.asp?id=2070
In the following exercises you must use
- as ... as
- not as ... as
- comparative + than
http://www.englisch-hilfen.de/en/exercises/adjectives_adverbs/adjectives_comparison_sentences2.htm
http://www.englisch-hilfen.de/en/exercises/adjectives_adverbs/adjectives_comparison_as_as.htm
http://www.english-4u.de/comparison_ex3.htm
http://www.english-4u.de/comparison_ex5.htm
http://www.english-4u.de/comparison_ex6.htm