--- Where is Jack? I can’t find him anywhere.
--- He his homework upstairs.
A. might have done
B. must have done
C. might be doing
D. must do
网友回答
A. might have done
B. must have done
(答案→)C. might be doing
D. must do
解析：本题考查情态动词表猜测的用法。结合语境Where is Jack?可知说话人想知道Jack现在在哪，谈论的是现在的事，排除AB; “在楼上做作业”应是正在进行，排除D。