What can we learn from the passage about Alaskans? [A] They are fond of bears. [B] They don't know how to treat tourists. [C] They want to frighten tourists away. [D] They live a very natural life.
【简答题】我国从2009年6月1日起正式实施《食品安全法》,从源头监管整个食品的生产和流通过程.2008年发生的“三鹿牌“粉事件就是由于不法生产厂家违规向原料奶中添加了化工产品三聚氰胺(化学式为C 3 H 6 N 6 )所致,已知三聚氰胺中碳元素化合价为+4价,则氮元素化合价是______价.下架的粉若进行焚烧处理,三聚氰胺在足量氧气中燃烧时生成三种物质,其中一种物质在空气中含量最多,请写出三聚氰胺...