句子分析
　　英文原句
　　Immediately adjacent to the timberline, the tundra consists of a fairly complete cover of low-lying shrubs, herbs, and grasses, while higher up the number and diversity of species decrease until there is much bare ground with occasional mosses and lichens and some prostrate cushion plants.
　　难点解析
　　本句难点在于大量的专有名词以及考生们比较陌生的词组用法，如：“a fairly complete cover of”“while higher up”。而且，“consists of…”的特殊用法也容易影响理解句意。
　　在句子分析的过程中，可以通过引导词while(通常作为对比关系连接词)，以及“immediately adjacent to…”和“higher up…”方位对比，将句子结构梳理开。然后，可拆出由“until”引导的“there is…”条件状语从句。
　　句子分析
　　子句类型 并列句
　　连 接 词 无逻辑连接词
　　子句内容 Immediately adjacent to the timberline, the tundra consists of a fairly complete cover of low-lying shrubs, herbs, and grasses.
　　语法分析 Immediately adjacent to the timberline, [状语] the tundra [主语] consists of [谓语] a fairly complete cover [宾语] of low-lying shrubs, herbs, and grasses. [定语]
　　子句翻译 苔原紧挨着树带界线，其中长满了低矮灌木，草本植物和草。
　　子句类型 状语从句
　　连 接 词 until
　　子句内容 There is much bare ground with occasional mosses and lichens and some prostrate cushion plants.
　　语法分析 There [表语] is [系动词] much bare ground [主语] with occasional mosses and lichens and some prostrate cushion plants. [定语]
　　子句翻译 存在几乎光秃的土地，上面偶尔会长有苔藓、地衣和匍匐状垫状植物。
　　子句类型 并列句
　　连 接 词 while
　　子句内容 Higher up the number and diversity of species decrease.
　　语法分析 Higher up [状语] the number [主语] and [连接词] diversity [主语] of species [定语] decrease. [谓语]
　　子句翻译 物种的数量和多样性会随着(海拔)的升高而下降。
　　全句翻译 苔原紧挨着树带界线，其中长满了低矮灌木，草本植物和草;物种的数量和多样性会随着(海拔)的升高而下降，直到剩下几乎光秃的土地，上面偶尔会长有苔藓、地衣和匍匐状垫状植物。
　　单词记忆
　　Immediately adjacent to the timberline, the tundra consists of a fairly complete cover of low-lying shrubs, herbs, and grasses, while higher up the number and diversity of species decrease until there is much bare ground with occasional mosses and lichens and some prostrate cushion plants.
　　lichen n. 地衣 moss n. 苔藓 shrub n. 矮灌木 timberline n. 树带界限 herb n. 草 adjacent adj. 临近的 low-lying adj. 低的 prostrate adj. 伏地的 cushion n. 垫子 tundra n. 苔原