高处作业区周围的孔洞、沟道等应设置安全标志，夜间还应设红灯示警(   )。

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69530' and id < 4505115 and id<>'4505115' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69530' and id > 4505115 and id<>'4505115' order by id asc limit 5