一旦刨子刨底表面不合乎要求，必须弃之不用。

现有A、B、C、D四种化合物，透过蓝色钴玻璃其焰色反应均为紫色，A、B、C和盐酸反应后，均可得到D；将固体C加热可制得A；若在A的溶液中通入一种无色无味气体，又可制得C；若B与C的溶液混合可制得A。

（1）推断A是________________，B是____________，C是___________，D是____________。

（2）写出B+CA的离子方程式：______________________。

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 presentation layer at the receiving machine changes the common format into its （） -dependent format.

A．receiver

B．user

C．server

D．customer

民用建筑中，混凝土基础断面的形式有（）。

A.矩形

B.锥形

C.阶梯形

D.圆弧形

因子A(印染)的自由度( )。

A．f_A=4

B．f_A=5

C．f_A=15

D．f_A=20