Even though there is plenty of evidence that the quality of the teachers is the most important variable, teachers' unions have fought against getting rid of bad ones and promoting good ones.关于本句语法的分析，下列选项正确的是（ ）。A. that 引导限制性定语从句，修饰 evidenceB. Even though 引导条件状语从句C. 主句主干为 the quality is importantD. 状语从句的主干为 there is plenty of evidence

本题考查状语从句的识别及句子主干分析。关键点在于：

1. Even though引导的是让步状语从句，而非条件状语；
2. there is plenty of evidence是状语从句的主干，that引导的同位语从句修饰evidence；
3. 主句的主干为teachers' unions have fought against...，而非选项中混淆的其他结构。

选项分析

A、that 引导限制性定语从句，修饰 evidence

错误。

• that引导的从句是同位语从句，用于解释说明evidence的具体内容（即“教师质量是最重要的因素”），而非修饰evidence的定语从句。

B、Even though 引导条件状语从句

错误。

• Even though表示“尽管”，引导让步状语从句，而非条件状语从句（条件状语通常由if、if only等引导）。

C、主句主干为 the quality is important

错误。

• 主句的主干应为teachers' unions have fought against...，the quality is important是状语从句中的内容。

D、状语从句的主干为 there is plenty of evidence

正确。

• 状语从句的完整结构为：Even though there is plenty of evidence that...，其主干为there is plenty of evidence，that引导的从句是同位语。