问题
选择题
--Who is the person talking with you just now?
-- Well, if you ______ know, his name is David.
A．may
B．can
C．must
D．shall
答案
答案：C
考查情态动词：A. may 可以，B. can能够， C. must 必须，偏要D. shall将会，句意是;--刚刚和你说话的是谁？--如果你偏要知道，是大卫。选C。