Madonna a straight A student,but it was dancing that she was really crazy about.
A. must be
B. could be
C. must have been
D. could have been
网友回答
A. must be
B. could be
C. must have been
D. could have been
解析： 考查情态动词。根据题干后一个分句中的过去时态可排除A、B两项；C项的意思是“一定是”；D项的意思是“本来能够是”。句意为：Madonna本来可以成为一个全优生，但是她真正着迷的是舞蹈。根据题意可知，D项正确。