说明：  pcb(印制电路板)布局布线指南讲座中的一些关于如何设计pcb的问题解答！有关于某些布线为什么要走蛇形线等问题解答！
(pcb (printed circuit board) layout guide to the lecture about how to design pcb' s questions! Why do some wiring on the snake-like lines, and questions to go!)