已知集合U={1，3，5，7，9}，A={1，5，7}，则CUA=[ ] A．{

搜题请搜索小程序“爱下问搜题”

问题选择题

已知集合U={1，3，5，7，9}，A={1，5，7}，则C_UA=[ ]

A．{1，3}

B．{3，7，9}

C．{3，5，9} 　

D．{3，9}

答案

答案：D

改错题

下列各句均有一处错误，请找出并改正。

1. I Would like seeing them too.

_________________________

2. Thank you for to help me.

_________________________

3. Look at the clouds. It rains.

_________________________

4. We are going on a trip if it won't rain tomorrow.

_________________________

5. Who have the biggest banana?

_________________________

6. Do they free this Saturday?

_________________________

单项选择题

重合指数法对（）算法的破解最有效。

A.置换密码

B.单表代换密码

C.多表代换密码

D.序列密码