13.A. must B. would C. should D. ought to
12.A. as B. while C. if D.unless
11.A. mysterious B. painful C. nervous D. noticeable
10.A. also B. perhaps C. exactly D. normally
9.A. waiting B. standing C. gathering D. asking
8.A. information B. survey C. motive D. explanation
7.A. proverb B. expression C. essay D. pattern
6.A. with B. to C. about D. on
5.A. was B. is C. had been D. be
4.A. like B. expect C. want D. attempt