56. Ultimately, however, our basic design strategy is focused not simply on being less bad but on creating completely healthful materials that can be either safely returned to the soil or reused by industry again and again.

　　【分析】本句为复合句。句子主干为our basic design strategy is focused not on being less bad but on creating healthful materials。that引导定语从句，修饰materials。however 意为 然而 ，是插入成分。not but 意为 不是 而是 ，连接两个介词短语。either or 意为 或者 或者 ，表示并列结构。 【译文】然而最终，我们的基本设计目标不仅是简单地关注于 较低危害 ，而是发明完全有益于健康的材料，这种材料或可以无害地回归土地，或可以被工业重复利用。 57. As you sleep you pass through a sequence of sleep states light sleep, deep sleep and REM sleep that repeats approximately every 90 minutes. 【分析】本句为复合句。主句主干为you pass through a sequence of sleep states。as引导时间状语从句，表示 当 时 。that引导非限制性定语从句，修饰a sequence of sleep states，that在从句中作主语。light sleep, deep sleep and REM sleep 是插入成分，具体说明 states 的内容。 【译文】人们睡觉时经历了一连串的睡眠阶段 浅度睡眠阶段，深度睡眠阶段，快速眼动睡眠阶段 大约每90分钟重复一次。 58.You program the clock with the latest time at which you want to be wakened, and it then duly wakes you during the last light sleep phase before that. 【分析】本句为并列复合句。句子主干为You program the clock, and it wakes you。at which 引导定语从句，修饰 time，which 在从句中作时间状语，at+时间是固定搭配，所以 which 之前加介词 at，表示在某一具体时间点。句末的 that 指代 the latest time。 【译文】将闹钟调好至你想起床的时间，它便会适时地在之前的最后一个浅眠期将你叫醒。 59. Home builders can now use materials such as paints that release significantly reduced amounts of organic compounds that don t destroy the quality of the air, water, or soil. 【分析】本句为复合句。主句为Home builders can now use materials。such as compounds是举例说明，作插入语。第一个 that 引导定语从句，修饰 paints;第二个 that 引导定语从句，修饰 materials。 【译文】房屋建造者们现在可以使用不破坏空气、水或土壤的材料，如释放少量有机物的涂料。

　　56. Ultimately, however, our basic design strategy is focused not simply on being less bad but on creating completely healthful materials that can be either safely returned to the soil or reused by industry again and again.

　　【分析】本句为复合句。句子主干为our basic design strategy is focused not on being less bad but on creating healthful materials。that引导定语从句，修饰materials。however 意为 然而 ，是插入成分。not but 意为 不是 而是 ，连接两个介词短语。either or 意为 或者 或者 ，表示并列结构。 【译文】然而最终，我们的基本设计目标不仅是简单地关注于 较低危害 ，而是发明完全有益于健康的材料，这种材料或可以无害地回归土地，或可以被工业重复利用。 57. As you sleep you pass through a sequence of sleep states light sleep, deep sleep and REM sleep that repeats approximately every 90 minutes. 【分析】本句为复合句。主句主干为you pass through a sequence of sleep states。as引导时间状语从句，表示 当 时 。that引导非限制性定语从句，修饰a sequence of sleep states，that在从句中作主语。light sleep, deep sleep and REM sleep 是插入成分，具体说明 states 的内容。 【译文】人们睡觉时经历了一连串的睡眠阶段 浅度睡眠阶段，深度睡眠阶段，快速眼动睡眠阶段 大约每90分钟重复一次。 58.You program the clock with the latest time at which you want to be wakened, and it then duly wakes you during the last light sleep phase before that. 【分析】本句为并列复合句。句子主干为You program the clock, and it wakes you。at which 引导定语从句，修饰 time，which 在从句中作时间状语，at+时间是固定搭配，所以 which 之前加介词 at，表示在某一具体时间点。句末的 that 指代 the latest time。 【译文】将闹钟调好至你想起床的时间，它便会适时地在之前的最后一个浅眠期将你叫醒。 59. Home builders can now use materials such as paints that release significantly reduced amounts of organic compounds that don t destroy the quality of the air, water, or soil. 【分析】本句为复合句。主句为Home builders can now use materials。such as compounds是举例说明，作插入语。第一个 that 引导定语从句，修饰 paints;第二个 that 引导定语从句，修饰 materials。 【译文】房屋建造者们现在可以使用不破坏空气、水或土壤的材料，如释放少量有机物的涂料。