问题补充：
“That VCD you bought very expensive” . “Do you know ? ”
A. ought to be ; how much it cost
B. may be ; how much it costs
C. must be ; how much it cost
D. can be ; how much doesn\t it cost
答案：
A. ought to be ; how much it cost
B. may be ; how much it costs
(答案→)C. must be ; how much it cost
D. can be ; how much doesn\t it cost
解析：根据语序排除D，A不合语意，B中第二空时态不符。
