20. That old man was so 　　　　　about everything that nobody could please him.

　　 A. unique　　　　 B. special　　　　　 C. specific　　　　 D. particular

19. I'll never forget the days 　　　　I learnt hard in my senior high school changed my whole life.

　　 A. that; which　 B. which; that　　 C. when; which　 D. which; when