模拟实现网桥的转发功能，以从文件中读取帧模拟网桥从网络中收到一帧，即从两个文件中读入一系列帧，从第一个文件中读入一帧然后从第二个文件中再读入一帧，如此下去。对每一帧，显示网桥是否会转发。-Analog implementation bridge forwarding function to read analog bridge frame　the file receive a frame　the network,　the two documents read in a series of frames,　the first file is read into a frame then　The second document read into a, and so on. For each frame, indicate whether the bridge will be forwarded.