某国际贸易中心共40层，设有载客电梯10部（用E0~E9标识）。利用多线程技术实现个电梯载客的仿真情况-an international trade center with a total of 40 layers, with 10 passenger elevators (E0 - E9 with logos). Use multithreading technology to achieve a passenger elevator of the simulation