---Where is my reference book? It was here a moment ago.---Someone it by mistake.
A. could have taken
B. must take
C. might take
D. must have taken
网友回答
A. could have taken
B. must take
C. might take
(答案→)D. must have taken
解析：在肯定句中对过去发生的事情的推测要用must have done。这里表示肯定有人错拿了。