对于数列{an}，定义数列{an＋1－an}为数列{an}的“差数列”，若a1＝ 发布时间：2017-04-30 13:05 │ 来源：www.tikuol.com 题型：填空题 问题： 对于数列{an}，定义数列{an＋1－an}为数列{an}的“差数列”，若a1＝1.{an}的“差数列”的通项公式为an＋1－an＝2n，则数列{an}的前n项和Sn＝________.
题型：填空题 用方框内所给单词的适当形式填空。 prefer; graduate; final; schedule; determine; valley; altitude; flow; bend; boil 1. The plane flew to a very high ____.2. The man jumped down to safety ____. 3. Here is a photograph of our village. Our village is in a ____. 4. She ____ down to tie her shoe laces.5. He said that he ____ English to maths. 6. They were ____ to face up to the difficulties. 7. After ____ he went abroad for further education. 8. The water is ____. Would you turn off the stove?9. The river ____ into the sea. 10. Has he made the exam ____? 查看答案