Embedded C is a set of（ ）for the C Programming language by the C Standards committee to address commonality issues that exist between C extensions for different embedded systems.
A. programming
B. database
C. interface
D. language extensions
The architecture of an embedded system is an abstraction of the embedded device，meaning that it is a（ ）of the system that typically doesn’t show detailed implementation information such as software source code or hardware circuit design.
A. specialization
B. computer
C. generalization
D. design
An embedded system is an applied computer system，as distinguished from other types of（ ）such as personal computers（PCs）or supercomputers.
A. computer systems
B. computer hardware
C. computer software
D. systems
以下关于层次化局域网模型中核心层的叙述，正确的是（ ）。
A. 为了保障安全性，对分组要进行有效性检查
B. 将分组从一个区域高速地转发到另一个区域
C. 由多台二、三层交换机组成
D. 提供多条路径来缓解通信瓶颈
POP3协议采用（ ）模式，客户端代理与POP3服务器通过建立TCP连接来传送数据。
A. Browser/Server
B. Client/Server
C. Peer to Peer
D. Peer to Server
集线器与网桥的区别是：（ ）。
A. 集线器不能检测发送冲突，而网桥可以检测冲突
B. 集线器是物理层设备，而网桥是数据链路层设备
C. 网桥只有两个端口，而集线器是一种多端口网桥
D. 网桥是物理层设备，而集线器是数据链路层设备