16. David wants to be _______ engineer while Cathy wants to be _______ doctor.
A. an; the B. the ; the C. an; a D. the;
17. The 16th Asian Games started _______ November 12th, 2010 in Guangzhou.
A. at B. on C. in D. by
18. Please do not feed the fish; they _____ die if they eat too much.
A. shall B. must C. need D. may
