It’s hard to say what kind of person he is. Sometimes he is very nice; at other times he be very cold.
A. must
B. will
C. shall
D. can
网友回答
A. must
B. will
C. shall
(答案→)D. can
解析：考查情态动词。must 必须，will 将会，shall 将会can 有时候可能会，句意：很难说他是哪种人。有时候他会很和蔼，有时候他非常冷酷。所以选D。