for 表推测的原因，句子重心在for前的分句，也可 以表示对主句的看法或解释。 It is going to rain, for it’s getting dark. He may be ill, for he is absent today.
because 和for的区别
1．for 是并列连词，只用于连接表示原因的分句，因此 不能用于句首。because表示原因时，可位于句首。
表示在…之前或在…之后， before & after Turn off the light before you leave.
I often play computer after finishing my homework. 表示自从，直到 since &until
She has studied very hard since she came to our school. 两者区别：1. till不能用于句首 2. 用在否定句中， 表示直到…才， 这个动作直到untill所表示的时候才 发生。
三，表示转折关系的连词 but 但是
he is old, but he is very healthy. however 然而，但是，可放在句首，中，末， 通常用
逗号隔开，作插入语。
My room is small, however, it’s very comfortable. while 然而，而
2. such +名/短语 that… It was such a warm day that we went out for a walk.
注意：such+a/an+形容词+单数名词结构

= so +形容词+a/an+单数名词结构
He told us such a funny story that we all laughed.
The thief was caught as/ when he was stealing in the supermarket. ②as表示 一边……一边……，强调从句和主句中两 个动作交替进行或同步进行。
They talked as they walked. ③as表示随着
As time goes on, it's getting warmer and warmer.
连词
什么是连词? 用于连接单词，短语或句子的词语
并列连词 从属连词
并列连词
表并弄关系的连词： 1. and 和，而且 基本用法：表并列
I like apples and oranges. 祈使句后用and, 有条件句作用 此时and= if you… you will…
because重心在because引导的从句
It’s morning, for the birds are singing. （对，表推断的原因）
It’s morning, because the birds are singing. （错，因为鸟叫不是天亮的直接原因）
但可以说the birds are singing because it’s morning.
unless= if not, 表示反面条件，如果不、除非。 They will go tomorrow unless it rains.
=（They will go tomorrow if it doesn't rain.） I won't let you in unless you show me your pass.
though 较口语，可作副词，且放在句首，句末，意 主为“不过，可是” It is hard work, I enjoy it, though.
二，表示选择关系的连词 1. either…or 要么…要么… 不是…就是… (就近原则)
Either you or I am going there tomorrow. She is either drunk or mad. Either you or she attends the meeting. 2. or 还是，或者，否则 Is she a teacher or a student? Hurry up, or we will miss the bus. 3. otherwise 否则 （可与or 互换） Get up quickly, otherwise you will be late for school.
【误】For he did not obey the rules, he was punished. 【正】Because he did not obey the rules, he was
punished.
2．for 表示的是推断解释，because强调动作发生的直 接原因。
It must have rained last night, for the ground is wet. (不可用because，因为地面湿不是天下雨的原因）
while用来引导延续性动作或状态的从句，强调主从句 的动作同时发生或持续。
①while通常表示一段时间，从句中要用持续性动词作 谓语。
she fell asleep while she was reading the newspaper. ②while有时可以作并列连词，表示对比，可译成……
because 和for的区别
The day breaks, for the birds are singing. (不可用because，因为鸟叫不是天亮的原因）
He went to bed early, because he was tired (直接的理由)
He must be tired, for he went to bed early. (间接的推断)
从属连词
用以引导名词性从句和状语从句的连词，由从属连 词所导的句子叫从句。
引导时间状语从句的： when, while, as, before, after, until, till等
when用来引导长时间的从句时， 从句中用短暂性 动词；用来引导长时间的从句时，用持续性动词。 当从句的主语与主句的主语相同时，be动词可省略
2. so that 为了，以便 I got up early so that I could catch the first bus.
引导结果状语从句的：so… that, such…that… 1. so + 形/副 that…
I am so tired that I can’t walk any longer.
然而…Байду номын сангаас。
I am fond of English while he likes math.
as 引导的从句中多用表示动作的动词，不用be动 词，且多是短暂性或发展变化的情况，可理解为“ 随着”
①as表示点时间时，从句中用短暂性动词；表示段 时间时，用持续性动词。as和when两者经常可以 通用。
引导条件状语从句的连词: if, unless, as long as if 如果，表示在某种条件下某事会发生，也可以表
虚拟或假设
If you ask him, we will help you. If I were you, I won’t do that. as long as 只要 Nothing is impossible as long as we try. There isn't any orange in the bottle.
Until you told me, I have no idea of it. Jim doesn’t go to bed until/till his mother is back. 表示一…就… as soon as, once I will tell you as soon as I hear from her.
When I got home, my family were already having dinner.
（when表示点时间）
When they were still talking and laughing, the teacher
came in. （when表示时间段）
When ( you are) in trouble, ask him for help.
3. neither… nor 既不…也不…, 两者都不… 连接两个并列主语时，谓语动词与最近的主语保持一 致。
Neither I nor he likes this song.
并列连词
4．Not only… but also…不但…而且… (就近原则) Not only the mother but also the children are ill. He not only washed the clothes but also cleaned the room
→ He told us so funny a story that we all laughed.
六，引导让步状语从句的：although, though, even though, even if
although, though 虽然，纵然， 不能与but 连用， 但可与yet连用
although 较正式，不可作副词 Although/though he is old, he is very healthy.
I am good at swimming while he is good at running. yet, 然而，可是
He studied hard, yet he fail the exam.
四，表示因果关系的连词 so 因此，所以 （不能与because连用） therefore 因此，所以 (比so正式，常与and连用) for 因为 与because的区别： for的句子重心在for前的分句，而