21. As a businessman, he is ______ successful, but as a father, he is ______ failure.
A. a; the B. the; a C. ×; a D. a; ×
22. As a student, you should try to ______ being late for your class.
A. avoid B. refuse C. prevent D. punish
23. — Can you tell me why more and more people choose to shop in a supermarket?
— Because it offers a great ______________ of goods.
A. mixture B. variety C. connection D. combination
