【单选题】以下脑卒中危险因素中属于不可改变的因素的是:
【单选题】What is the main idea of the passage?
A.
A weatherman is giving a forecast of tomorrow's weather conditions in the country.
B.
A weather analyst is reviewing the weather conditons of the past two days.
C.
An announcer is discussing possible changes in the weather over the next few days.
D.
The local weather channel is announcing a sudden change of weather tomorrow.
【单选题】What is the main idea of the passage?
A.
The local weather channel is announcing a sudden change of weather tomorrow.
B.
A weatherman is giving a forecast of tomorrow’s weather conditions in the country.
C.
A weather analyst is reviewing the weather conditions of the past two days.
D.
An announcement is discussing possible changes in the weather over the next few days.
【单选题】1840年,( )发动了侵略中国的鸦片战争。
【单选题】下列关于消息认证码的说法中错误的是()。
D.
MAC 利用密钥来生成一个固定长度的短数据块
【单选题】1840年,( )发动了侵略中国的鸦片战争。
【单选题】下列关于消息认证的说法中,错误的是
A.
消息认证是验证所收到的消息确实来自真正的发送方,并且未被篡改的过程
D.
哈希函数的输入是可变大小的消息,输出是固定大小的哈希值
【单选题】下列关于消息认证的说法中,错误的是
B.
消息认证码是一种认证技术,它利用密钥来生成一个固定长度的数据块,并将该数据块附加在消息之后