线性表L=(a1，a2，…，an)用数组表示，假定删除表中任何一元素的概率相同，则删除一个元素平均需要移动元素的个数为______。
参考答案：(n-1)/2
用所给动词的适当形式填空。
1. It's twelve o'clock now. The students _____ (have) their lunch.
They _____(have) rice, meat and vegetables for their lunch.
2. Amy _____ (watch) TV every day. She _____ (watch) TV now.
3. Do you need much time _____(finish) _____(do) your homework?
4. I'd like _____(spend) half an hour _____(practise) _____(read) English.
5. Do you want _____ (I) _____ (ask)_____ (he)_____ (call) _____ (she) for
help.
6. Do you mind _____(open) the window? It’s too hot inside.
7. —Where's Kitty?
—She _____(dance) over there.
8. She _____(lie) in bed at the moment.
9. The teacher _____(write) e-mails at the moment.
10. Hobo needs a lot of money _____(buy) some interesting books.
衣服上有酱油渍怎么办？
