同期操作的要求有哪些？
["\u7b54\uff1a\u76f8\u5e8f\u3001\u76f8\u4f4d\u4e00\u81f4\u3002\u9891\u7387\u5c3d\u53ef\u80fd\u76f8\u7b49\uff0c\u5141\u8bb8\u9891\u7387\u504f\u5dee\u4e0d\u8d85\u8fc7\u00b10.50Hz\u3002\u7535\u538b\u5c3d\u53ef\u80fd\u76f8\u7b49\uff0c\u5141\u8bb8\u7535\u538b\u504f\u5dee\u4e0d\u8d85\u8fc7\u00b120%\u7684\u989d\u5b9a\u7535\u538b\u503c\u3002"]