Why does the man go to see his professor？
A. To prepare for the next midterm
B. To clarify a question from the midterm
C. To find out his grade on the midterm
D. To complain about his grade on the midterm
设集合A＝｛1，2，a，b｝，B＝｛2，4，c，d｝，已知A ∪ B＝｛1，2，3，4，5，6｝，A ∩ B＝｛2，4)，A－B＝｛1，3｝，那么a，b，c，d可以是[ ]．
A. a＝3，b＝5，C＝1，d＝5
B. a＝5，b＝6，C＝3，d＝5
C. a＝4，b＝5，C＝3，d＝6
D. a＝3，b＝4，C＝5，d＝6
According to the professor, what does the term balletti mean？
A dramatic story
B. A parade of horses
C. A dance done in figures
D. An outdoor entertainment
What did the man do wrong？
A. He did not finish the test within the time limit.
B. He did not study enough before the test.
C. He did not answer one question completely.
D. He did not understand a major concept.
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