求翻译：灵感仿佛是公共汽车，用不着它时只见路上一辆接一辆，等到真想乘了，守候半天连影子也不见。是什么意思？

Inspiration is like a bus, I saw a bus after bus on the way when you don't need it, really want to take up, waiting for a long time even the shadow has disappeared.