---Carl, why not go and help your sister water the flowers there?

---Why__________? I’m busy myself. Jack is lying on the grass doing nothing.

A．me

B．I

C．him

D．he

对于长度为n的顺序存储的线性表，当随机插入和删除一个元素时，需平均移动元素的个数为 【1】 。