计划就是根据环境的需要和自身的特点，确定在一定时期内的目标，并通过计划的编制，协调各

CT扫描中，对射线束的要求不包括

A．形状
B．大小
C．质量
D．运动的路径
E．运动的方向

一批价值为人民币480元的工艺品货样，经海关审核认为其价格可以接受并且数量合理，该货样关税税率10%，增值税税率17%，海关应征( )。

A．0元关税，0元增值税

B．48元关税，89.76元增值税

C．0元关税，13.6元增值税

D．8元关税，89.76元增值税

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（5）处应选择（）

A.receiver

B.user

C.server

D.customer

已知一定温度下合成氨反应：；△H＝—92.4kJ·mol^—1。在相同温度、相同体积的密闭容器中进行如下实验：①通入1molN₂和3molH₂达平衡时放出热量为Q₁；②通入2molN₂和6molH₂，达平衡时放出热量为Q₂，则下列关系正确的是(　 )

A．Q₂＝2Q₁

B．

C．Q₁<Q₂<184.8kJ

D．Q₁＝Q₂＜92.4kJ

简述GM系列直流断路器的灭弧原理和脱扣器的种类？