托福阅读100个长难句精选汇总深度解析：Gills were undoubtedly...

　　原句案例：

　　Gills were undoubtedly the main source of oxygen for these fish, but the lungs served as an auxiliary breathing device for gulping air when the water became oxygen depleted, such as during extended periods of drought.

　　结构分析：

　　复合句： 句1， but 句2， when 时间状语从句。

　　句子分析：

　　Gills were undoubtedly the main source of oxygen for these fish， 句1中，gills主语，were undoubtedly the main source 系表结构。of oxygen for these fish ，介词结构作定语。本部分意思：鳃无疑是这些鱼获得氧气的主要来源。

　　but the lungs served as an auxiliary breathing device for gulping air， 句2中，the lungs 主语，served as 谓语，an auxiliary breathing device 宾语，for gulping air 定语。本部分意思：肺可以充当一个辅助呼吸装置。

　　when the water became oxygen depleted, such as during extended periods of drought. 时间状语从句中，the water 主语， became oxygen depleted, 系表结构作谓语。such as during extended periods of drought 这个举例说明的部分，是从句的同位语(如果你不好理解这个概念，就当作举例说明来理解吧。)本部分意思：但当水中氧气耗尽时，比如在长期干旱时。

　　参考翻译：

　　鳃无疑是这些鱼获得氧气的主要来源，但当水中氧气耗尽时，比如在长期干旱时，肺可以充当一个辅助呼吸装置。

　　托福阅读中的长难句虽然会对考生造成一定的干扰，但只要考生具备了快速看懂理解它们的能力，其实长难句也并非难以应对，希望本文内容能够帮助大家提升阅读实力拿到高分好成绩。