A useful definition of an air pollutant is a compound added directly or indirectly by humans to the atmosphere in such quantities as to affect humans, animals，vegetation，or materials adversely.
(特殊结构such…as to——如此…以致)
空气污染物的一个有用定义是：一种直接或间接加入到空气里的化合物，其数量足以对人类、动物、植物或物质产生不利影响。
分句1.A useful definition of an air pollutant is a compound added directly or indirectly by humans to the atmosphere
分句2.in such quantities as to affect humans, animals，vegetation，or materials adversely
1和2嵌套
分句2是分句1的补语
版权声明：本文系网独家稿件，版权为网所有。转载须注明来源及作者，否则必将追究法律责任。
微信扫描下方二维码，第一时间知晓托福考试真题预测及解析，还有北美留学最新动态喔~(微信号：toefl120)!