[本科]高频保护的信号有闭锁信号、允许信号和（  ）。

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69478' and id < 4500868 and id<>'4500868' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69478' and id > 4500868 and id<>'4500868' order by id asc limit 5