21. One of _______ most common illnesses in our society is “time sickness”, _______ sense of time pressure and hurry that causes anxiety and tension.

A. /; a             B. /; the           C. the; a           D. the; the

22. It is clear that in modern society high ____________ and demands are placed on teachers. 

A. motivations           B. expectations          C. standards              D. opportunities

23. As a student of Senior Three, he has very little free time _________ he can spend developing his own interest.

A. when           B. in which         C. at which             D. that