2018考研英语：长难句练习及解析（8）

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The energy used to separate oxygen from air before burning is almost as great as that needed to filter out nitrogen afterwards, leading to a similar loss of efficiency.
    【核心词汇】
    separate v.使分离，使分开
    filter v.过滤，渗透
    efficiency n.效率，效能
    lead to 导致
    【结构分析】本句是主系表结构，主干是The energy used to separate oxygen from air before burning is almost as great as that needed to filter out nitrogen afterwards，使用了as...as...结构，其中被比较的对象that needed to filter out nitrogen afterwards中，that指代上文的energy，过去分词结构needed to...作后置定语体现被动。其中主语energy由过去分词结构used to separate oxygen from air before burning作后置定语体现被动;句末的现在分词结构leading to a similar loss of efficiency做全句的结果状语。
    【参考译文】燃烧前将氧气从空气中分离所需要的能源几乎与随后将氮气过滤所需的耗费一样多，这就使得两者在效率损失上不相上下。