题目内容
据报道,某些建筑材料会产生放射性同位素氡
,从而对人体产生伤害,该同位素原子的中子数和质子数之差是
试卷相关题目
SQL Error: select id,body,options from ***_enewstiku_ where sourceid='20603' and id < 1800112 and id<>'1800112' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='20603' and id > 1800112 and id<>'1800112' order by id asc limit 5