问题补充：
Dad, my computer is broken. Must it now?
A. is repaired
B. has been repaired
C. be repaired
D. has repaired
答案：
A. is repaired
B. has been repaired
(答案→)C. be repaired
D. has repaired
解析：句意：爸爸，我的电脑坏了。它必须现在修理吗？It指代电脑，它与repair修理是被动关系，要用被动语态，系动词be+动词过去分词；句中有情态动词must，所以be要用原形，故选C。
