The presentation layer is concerned with the （）and semantics of the information exchanged between two systems. The processes in two systems are usually exchanging information in the form of character （）, numbers, and so on. The information should be changed to bit （） before being transmitted. Because different computers use different encoding systems, the presentation layer is responsible for （） 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 （） -dependent format.

The information should be changed to bit （）before being transmitted.

A．systems

B．characters

C．layers

D．streams

肖邦和李斯特都是浪漫主义乐派的代表人物，他们作品的风格特点是（）。

A.重视调性的平衡、严谨、规整，以主调风格为主导

B.富于色彩和感情，含有许多主观主义和空想的因素

C.抽象的、超越现实的，采用短小的、不规则的乐曲形式

D.无视调性规则，追求无限自由，采用线形的自由对位法