—Why didn’t Susan come to school? —I don’t know. She ill.A. could beB. may have beenC. mig

问题补充：

—Why didn’t Susan come to school?

—I don’t know. She ill.

A. could be

B. may have been

C. might

D. must have been

答案：

A. could be

(答案→)B. may have been

C. might

D. must have been

解析：本题回答语表示的含义是苏珊可能生病了，所以导致的后果是她未能上学，故用情态动词may+完成时态的结构，故本题选B。