4.一体化机车信号主机自左至右分别是哪些板件？
["\u7b54\uff1a\u81ea\u5de6\u81f3\u53f3\u4e3a\u8bb0\u5f55\u677f\u3001A\u5957\u4e3b\u673a\u677f\u3001B\u5957\u4e3b\u673a\u677f\u3001\u8fde\u63a5\u677f\u3001\u7535\u6e90\u677f1\u3001\u7535\u6e90\u677f\uff12\u3002"]