钴-60的半衰期为

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku where sourceid='29408' and id < 2394699 and id<>'2394699' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='29408' and id > 2394699 and id<>'2394699' order by id asc limit 5