认证技术的主要功能有______两个方面。A．验证发送者身份和信息_爱下问搜题

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问题单项选择题

认证技术的主要功能有______两个方面。

A．验证发送者身份和信息的完整性

B．验证发送者身份和信息的源地址

C．验证发送者的口令和信息的目的地址

D．验证发送者的口令和身份

答案

参考答案：A

解析：认证技术的主要功能有两个方面；其一，验证信息的发送者的真正身份，防止被人冒充；其二，保证信息在传送过程中未被篡改和伪造，即信息的完整性。

补全对话，情景问答

从B栏中找出与A栏相对应的答语。

                                  A
( )1. What are your favourite clothes?
( )2. I like your skirt.
( )3. I like skirts.
( )4. Whose pants are these?
( )5. Is this your hat?
( )6. What' s your favourite colour?
( )7. How many trees can you see in the picture?
( )8. Are they new?
( )9. Do you like English?
( )10. Thank you very much.

                                  B
A. No, it isn't. It's too big.
B. Thanks.
C. We're the same.
D. You're welcome.
E. Yes, I do. Very much.
F. Yes, they're new. They're from my mom.
G. Shirts are my favourite clothes.
H. Red.
I. They are Li Ming's.
J. I can see six.

填空题

删除课程表中“备注”字段的命令是：ALTER TABLE 课程表（）。