设计一个电梯模拟系统。这是一幢9层楼（有一地下层）的仿真离散模拟程序，因为它实现了并行（微观上串行，宏观上并行）的模拟，即用户即时输入与程序运行的并行。-To design a lift simulation system. This is a nine-storey (with a basement) discrete analog simulation program, because it implements a parallel (serial micro and macro in parallel) simulation, that is, the user input and real-time program runs in parallel.