题目

On any weekend throughout the year one can spend hours browsing through neighborhood flea （跳蚤） markets．These are very popular for those who are in search of bargains and who have a keen eye for picking through what others have discarded．They hunt and search for something they can reuse．Americans love secondhand merchandise （商品） which can be bought cheaply and restored to its original use．In many cases the condition and the quality are still good, though the style might be outdated．        For some people searching through flea markets is a hobby which reaps rewa二氧化硫是大气的一种主要污染物,下列关于二氧化硫的叙述正确的是( )A.二氧化硫是由硫、氧两种原子组成的B.二氧化硫是由硫和氧气分子构成的C.二氧化硫分子是由硫、氧两种元素组成的D.一个二氧化硫分子是由1个硫原子和2个氧原子构成的