搜题请搜索小程序“爱下问搜题”
问题 单项选择题

设等差数列an的公差d≠0，a1=9d，若ak是a1和a2k的等比中项，则k=（）。

A.12

B.10

C.8

D.6

E.4

答案

参考答案：E

解析：

由题有，解得k=4或-2，因为k＞0，因此k=4。

填空题

______发育成果实．______发育成果皮，子房里面的______发育成种子，胚珠里面的______发育成胚．
查看答案
单项选择题

For each blank, choose the best answer from the four choices and write down on the answer sheet.

（）is a channel’s capacity which directly reflects the data transfer rate of the channel.

（）functions in a NetWare network which is used to define addressing schemes.

（）is a network layer device that supports multiple LAN interfaces and segments LANs into smaller collision and broadcast domains.

（）is the popular LAN developed under the direction of the IEEE802.3.

（）is a device which enables digital microcomputers to communicate across analog telephone lines.

（）functions in a NetWare network which is used to define addressing schemes.

A． NetBEUI

B． IP

C．IPX

D．NCP
查看答案