The presentation layer is concerned with the (1) and semantics of the information exchanged between two systems. The processes in two systems are usually exchanging information in the form of character(2), numbers, and so on. The information should be changed to bit (3) before being transmitted. Because different computers use different encoding systems, the presentation layer is responsible for(4) between these different encoding methods. The presentation layer at the sender changes the information from its sender-dependent format into a common format. The presentation layer at the receiving machine changes the common format into its(5)-dependent format.

空白（2）处应选择（）

A.numbers

B.functions

C.strings

D.codes

张鹏对电脑说“请关机”，电脑马上执行关机命令，这其中主要应用了人工智能中的（）。

A.图像识别技术

B.指纹识别技术

C.语音识别技术

D.字符识别技术