—I’m afraid you missed a fantastic lecture yesterday. How come you were absent from it?—If

问题补充：

—I’m afraid you missed a fantastic lecture yesterday. How come you were absent from it?

—If you know, I asked for a day off and visited a relative of mine in hospital.

A. might

B. may

C. shall

D. must

答案：

A. might

B. may

C. shall

(答案→)D. must

解析：句意：--恐怕你昨天错过了极好的讲座。你怎么会缺席的？--如果你偏要知道，我请了一天假去看完医院的亲戚。Must必须，偏要，may可以，可能，shall应该，将会，所以选D。