a) Manager (менеджер/управляющий), secondary (вторичный), different (различный/другой), appearance (внешность), comfortable (удобный), musical (музыкальный), tasty (вкусный), conversation (разговор), economic (экономический), recently (недавно), profession (профессия), fashion (мода), properly (правильно/должным образом), early (ранний+рано), satisfaction (удовлетворение), friendly (дружелюбный), condition (состояние).
nouns: manager, appearance, conversation, profession, fashion, satisfaction, condition.
adjectives: secondary, different, comfortable, musical, tasty, economic, early, friendly.
adverbs: recently, properly, early.
b)differ: difference, different, indifferent
comfort: comfortable, uncomfortable, discomfort
friend: friendly, unfriendly
music: musical, musically
appear: appearance, disappear
c) 1. My friend studies at the economic college.
2. They are friends and get along well with each other.
3. We live in a comfortable room.
4. You should take care of your appearance.
5. There are many different shops in this street.
1) more dangerous
2) the most polite
3) more little
4) more expensive
5) the hardest
6) more stressful
7) more interesting
8) better