模拟量转换为数字量由模数转换器进行，称做：()
A．B／D转换
B．A／D转换
C．D／B转换
D．A／B转换
E．A／C转换
参考答案：B
— Why did you talk to the teacher after class?
— I don't understand ________ during the lecture.[ ]
A. the problem did she tell us
B. how did she say
C. that she was talking about
D. what she was teaching
公钥体系中，私钥用于 （69） ，公钥用于 （70） 。
69（）
A．解密和签名
B．加密和签名
C．解密和认证
D．加密和认证
