—— I haven’t seen Johnson these days.—— I think she a conference in Beijing but I’m not

问题补充：

—— I haven’t seen Johnson these days.

—— I think she a conference in Beijing, but I’m not sure.

A. should be attending

B. might be attending

C. could have attended

D. must have attended

答案：

(答案→)A. should be attending

B. might be attending

C. could have attended

D. must have attended

解析：本题考查情态动词。句中should表示“应当”之意。句意：——这些天我没有看到Johnson。——我想她一定在北京从句会议，但我不确定。