复合句：(complex sentence)
复合句是由主句+从句构成，它是英语学习中比较复杂的句子结构。一般来说，英语中一个句子只能有一个谓语，如果出现两个谓语，那么其中一个谓语只能是以从句的形式或并列句或非谓语动词的形式出现。所谓从句是指从属于主句的句子，由从属连词连接。从句的种类有很多，但根据其性质和作用可以分为：名词性从句，形容词性从句(即定语从句)，副词性从句(即状语从句)三大类。
a. 定语从句(Attributive Clause)这是出现在阅读题型中最多的从句!重要!
定语从句：在句中做定语，修饰一个名词或代词。
先行词：被定语从句修饰的名词,词组或代词。
关系词：引导定语从句的词;一般紧跟在先行词后引出定语从句。分为关系代词和关系副词。
关系代词有：who, whom, whose, that, which等。
关系副词有：when, where, why等。
关系词常有3个作用：1，引导定语从句。2，代替先行词。3，在定语从句中担当一个成分。
例如:
Once upon a time, there was a king (who had a small kingdom).
先行词 关系词
For one thing, the tigers ( that were kept in the zoo) were often used in court.
先行词 关系词
There came out a young lady ( whose hair was golden).
先行词 关系词
They would meet on the night ( when there was a full moon in the sky).
关系代词引导的定语从句
关系代词在定语从句中作主语时，从句谓语动词的人称和数要和先行词保持一致。
(1) A teacher is a person who passes knowledge to the student.
(2) The book that is on the desk was written by Yao Ming.