环保是我国的一项基本国策，空气的净化日益受到人们的关注，下列气体组中的各种气体都属于空气污染物的是（   ）

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My name is Scott．I am an American boy．I am thirteen years old，Now I am a student in Great School in Dalian，Liaoning．I am in Class One，Grade Seven．I like sports．My favourite sport is table tennis．But I can 't swim．My mother is a music teacher．

She can sing and dance．can the，play，she，piano(?)Yes，she can．My father is a hotel manager．He can speak Chinese，English，Japanese and Russian．He is popular in the hotel．

根据短文内容，完成下列各题。