16.Mr. Hall understands that ______ maths has always been easy for him， it is not easy for the students.
A. unless
B. since
C. although
D. when
17.When you answer questions in a job interview， please remember the golden rule： Always give the monkey exactly ______ he wants.
A. what
B. which
C. when
D. that
18.______ is going to America for further study.
A. He is said that
B. People said that he
C. It was said he
D. It is said that he
19.Mary ______ be in Paris，for I saw her in the town only a few minutes ago.
A. mustn‘t
B. can’t
C. shouldn‘t
D. may not
20.— The room is so dirty. ______ we clean it?
— Of course.
A. Will
B. Shall
C. Would
D. Do