—I didn’t see her yesterday I looked for her everywhere but couldn’t find her.—Oh but you.

问题补充：

—I didn’t see her yesterday,I looked for her everywhere,but couldn’t find her.

—Oh,but you.She was working in the office.

A. must have

B. ought to

C. ought to have

D. can’t have

答案：

A. must have

B. ought to

(答案→)C. ought to have

D. can’t have

解析：从题意来看，她在办公室里工作，却没有被找到，实际上是应该找得到的，表示应该能做到某事而未能做到，用ought to(或should)+动词的完成式，结合本题的选项应选C。