21．According to a survey , ________daydreaming is ________means of relaxation.
A．the；a B．/；the C. /；a D．a；the
22. As a matter of fact, my attitude towards the case was different from ________ of my father.
A. that B. this C. what D. one
23. As far as I know, Kate is a girl, whom you cannot easily persuade to change her mind.
A. grateful B. extreme C. sincere D. stubborn
