问题
选择题
Look! My father_______ with my teacher. [ ]
A. talking
B. are talking
C. talks
D. is talking
答案
答案：D
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Look! My father_______ with my teacher. [ ]
A. talking
B. are talking
C. talks
D. is talking
答案：D
。则删除时的平均移动数为 (40) 。