句子：简单句（主谓宾、主系表）、复杂句（并列句、复合句）
复合句：包含从句的句子
从句：定语从句（Adj. clause）、名词性从句(Noun. clause)、状语从句(Adv. clause)
名词性从句：主语从句、宾语从句、表语从句、同位语从句
定语从句：当一个句子作定语时，这个句子就叫定语从句
位置：被修饰词后
引导词：
关系代词：that, which, who, whose, whom（代指一个名词，在从句中作主语或宾语）
关系副词：where, when, how, why（代指一个介词短语，在从句中作状语）
1、The girl who wears a red dress is my sister. (who代指the girl, 作从句主语)
2、I like the book that I borrowed from you. (that代指the book,作从句宾语)
3、I like the book whose cover is blue.(whose cover代指the book’s cover, 作从句主语)
4、She is the girl with whom I want to travel. (whom代指the girl,作从句宾语)
5、This is the place where we met for the first time. (where=in which代指in the place，作状语) 主句：This is the place. 从句：We met for the first time in the place. ---we met for the first time in which--- in which we met for the first time (in which=where)
区别：This is the place that I want you to see. (主句：This is the place. 从句：I want you to see the place. 代指the place 用that)
6、Vocation is a period of time when/in which we can enjoy ourselves.
主句：Vocation is a period of time. 从句：We can enjoy ourselves in the period of time. Vocation is a period of time that I can not forget.
7. This is the reason why I love you. (why=for which)
This is the reason. I love you for the reason.
8. This is the way how I helped her. (how=in which)
关系副词（where, when, how, why）=介词+which
限定性定语从句和非限定性定语从句的区别：
I like sports, which can help me keep fit.（我喜欢运动，它能帮我保持身材。
）
I like sports which can help me keep fit. （我喜欢那些能帮我保持身材的运动。
）
限定性定语从句：没逗号，表示限定修饰，翻译成汉语时，要把从句翻译到被修饰词前，那个……的；那些……的某物
非限定定语从句：有逗号，表示补充，汉英语序一致
例如：Students who have studied hard passed the exam. 那些学习努力的学生通过了考试。
Students, who have studied hard passed the exam. 学生都很努力，他们都通过了考试。
名词性从句：主语从句、宾语从句、表语从句、同位语从句
引导词：wh全套，that
What/that区别：what强调内容、东西，在从句中一般代指主语或宾语；that不强调任何内容，不作任何成分，没有任何实际含义
What my mother bought is my favorite. (主语从句)
I like what my mother bought.(宾语从句)
This is what my mother bought.(表语从句)
主语从句：
What my mother bought is my favorite.
Where/When/Why/How/Whether the meeting will be held is unknown.
Who will be the class president is unknown.
That引导的主语从句，通常用it作形式主语，把真正主语放在后面。
（that在此句中不作任何成分，没有任何实际含义，只起到引导的作用，但不能省略）
1.It is +动词过去分词+that从句
It is said that he has a beautiful girlfriend.（That he has a beautiful girlfriend is said. 头重脚轻）It is reported that…
It is suggested that…
It is commonly believed that…
2.It is +形容词+that从句(从句谓语通常用（should+）动词原型)
It is important that I (should) read English every day.
It is necessary that I get up early every day.
3.It is +名词+that从句
It is my pleasure that I can help you.
It is my honor that I can stand here and give you a speech.
4.It+不及物动词+that从句
It seems/appears that…似乎……
It happens that…碰巧……
宾语从句注意事项：
1.当宾语从句引导词是that时，that可以省掉，比如：I think (that) she is beautiful.但是当
that引导多个宾语从句并列时，只有第一个从句的that可以省，后面从句的that不能省。
比如：He insists (that) he is in good health and that he should be sent to work in Tibet.
2.当主句谓语动词是命令、请求、要求、建议（insist, suggest, require, order, recommend）,
从句谓语要用（should）+动词原型。
My mother suggests that I (should) read English every day. (suggest:建议；表明，作建议讲时，符合该条款；作表明讲时，谓语不需要遵从该条款；insist：坚持说；坚持要求做：作坚持要求做某事时，符合该条款；作坚持说讲，不需要遵从该条款)
3.从句和主句通常要保持时态一致，客观真理除外。
例如：My mother said that I was a good child.
My mother said that the earth travels around the sun.
4.否定转移：当主句谓语动词是think, believe, guess, suppose等词时，从句的否定要转移
到主句。
例如：I think that she is beautiful. ---I don’t think she is beautiful.
5.当从whether和if当中选一个表示是否的词时，直接选whether
6.当引导词是疑问词时，从句语序是疑问词+陈述句语序
表语从句注意事项：
当引导词是that时，千万记得不要漏掉。
The fact is that the most beautiful girl in my class does not have a boyfriend.
同位语从句：（引导词只有that,没有实际含义，不作任何成分，不能替换不能省略）
能跟同位语从句的词：advice, suggestion, fact, news, message, conclusion, idea, opinion…
The news that I passed the test made me happy. (同位语从句)
The news (that) you told me made me happy. （定语从句）
That引导同位语从句和定语从句异同点：
同：都跟在名词后
不同：同位语从句=前面名词的内容，定语从句只对前面名词起到修饰作用。
在定语从句中，that通常代指一个名词，，有时可用which代替，在从句中作宾语或主语，作从句宾语时，可以省略；在同位语从句中，that没有实际含义，不作任何成分，不能替换不能省略。
状语从句：
时间状语从句、地点状语从句、原因状语从句、方式状语从句、目的状语从句、结果状语从句、让步状语从句、条件状语从句……
注意事项：
1、状语从句只是整个主句的状语部分，不能和主句分开。
2、当状语从句前置时，通常在主句和从句见加逗号；当状语后置，主句和从句之间通常不
加标点。