DES算法是分组加密算法，它利用密钥，通过传统的换位、替换和运_爱下问搜题

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问题单项选择题

DES算法是分组加密算法，它利用密钥，通过传统的换位、替换和运算等变换实现二进制明文的加密与解密。（）

A．异或

B．或

C．与

D．非

答案

参考答案：A

完形填空

Half a year before graduation from college, my son began to seek a job. __1__ the financial crisis(危机), fewer companies would like to __2__ new staff. My son targeted a company that was __3__ to hire only one person __4__ there were more than twenty people filling their resumes(简历).
After the interview, there would only be 3 who could enter the final round, which would later ____5____ one person to be employed. Everything seemed to go quite ____6____ and my son passed the first round and entered the final round in a week.
On the day of the final interview, my son and other two __7__ arrived at the interview place on time, __8__ the test. Unexpectedly, the interview was unbelievably __9__. The interviewer only said to them, “All of you are very super. Please go home and wait for our __10__. We will tell you the __11__ in 3 days. Good luck to all of you!” On the morning of the third day, my son received a text from the company shortly after breakfast that he was not employed. We all felt very __12__.
In nightfall that day, my son suddenly told me __13__ on the phone, “Dad, I have been employed!” Greatly surprised, I could not wait to ask him, “What’s the whole __14__?” My son told me that he received another text saying that he was employed. Actually the first text sent to my son was also __15__ of the test in the interview. Three men received the same text this morning and only my son’s __16__ was “Thank you” while the others said “Goodbye”.
Only then did I know that my son’s “hope” __17__ in that way. That is, when you feel disappointed, do not __18__ to say “thank you” to the one who disappoints you. Saying “thank you” shows respect for others’ work and shows your grand __19__. Therefore, while under the same condition, you will get the upper hand in terms of __20__ compared with others!

D．Contrary to

A．waiting for

B．watching over

C．thinking about

D．looking into

A．information

C．disappointed

D．personality

D．opportunities

单项选择题

下列哪些攻击属于服务攻击( )
Ⅰ．邮件炸弹攻击 Ⅱ．源路由攻击 Ⅲ．地址欺骗攻击 Ⅳ．DOS攻击

A．Ⅰ和Ⅱ

B．Ⅱ和Ⅲ

C．Ⅱ和Ⅳ

D．Ⅰ和Ⅳ