题目

氮元素是生命活动、物质间转化的常见元素。（1）图a是元素周期表中N元素的有关信息，图a中横线上缺失的具体内容是         。15N是N元素的一种重要核素，其一个原子核中含有的中子数为         。（2）三聚氰胺的结构简式如上图b，根据你的了解，下列关于三聚氰胺的表述中，正确的是          (填字母序号)。A．三聚氰胺的熔点可能很高    B．三聚氰胺的含氮量高达67%左右       C．三聚氰胺属于无机化合物    D．三聚氰胺分子--- I don’t suppose the police know who did it.   --- Well, surprisingly they do. A man has been arrested and ____ now.   [     ]A. has been questioned       B. is being questioned  C. is questioning           D. has questioned