连词
连词是一种虚词， 它不能独立担任句子成分而只起连接词与词，短语与短语以及句与句的作用。连词主要可分为两类：并列连词和从属连词。
一．并列连词：用来连接平行的词、词组和分句。
1、and
(1)连接两个并列的谓语：
They sat down and talked about something.
(2)连接两个并列的动词不定式，第二个不定式往往省略to：
They started to dance and sing.
(3)可以和祈使句或名词词组连用表示条件（or也有此用法）：
Make up your mind, and you'll get the chance.
= If you make up your mind, you'll get the chance.
One more effort, and you'll succeed.
= If you make one more effort, you'll succeed
(4)当表示整体或者指同一人时谓语动词用单数, 当and连接的单数名词前分别有each，every，no等词修饰时，谓语也用单数。
The bread and butter is really delicious(美味的).
The mother and teacher is very strict with her son.
No teacher and no student is allowed to smoke in class.
(5)连接两个相同意思的词，表示“渐渐”，或加强语气：
Read it again and again
2、both „and 两者都
Both he and she play the piano.
3、neither„nor 既不„也不„
谓语动词采用就近原则，与nor后的词保持一致。
Neither you nor he is to blame.
4、not only„but (also) 不但„而且„
She plays not only the piano, but (also) the guitar.
*not only„ but also 关联两个分句时，一个分句因有否定词not 而必须倒装。 Not only does he like reading stories, but also he can even write some.
5、as well as 也，与„一样
The teacher, as well as the students, is interested in the activity.
二．表示选择关系
1) or 或者
Which do you prefer, coffee or juice ?
Hurry up, or you'll be late for the class.
2) either„or或者„或者„（谓语动词采用就近原则）
Either you or I am right.
3) or else/ otherwise 否则
Be silent, or else you will be kicked out.
I am tired, otherwise, I would play.
三．表示转折或对比关系
1) but 但是
He is rich but unhappy.
2) while 然而（表示对比意味）
Some people love cats, while others hate them.
3) yet 然而
She said she would be late, yet she arrived on time.
4) however 然而，可是
She does not like him, however, I like him.
5) not„but„ 不是„而是„（not 和but 后面的用词要遵循一致原则） It's not my book, but is his book.
四．表示因果关系
1) for 因为（做并列连词使用时，是在对先行的句子补述原因或者理由，只可以连接句子与句子，通常不置于句首）
He is absent today, for he is ill.
2) so, therefore 因此
He hurt his leg, so he couldn't play in the game.
I think, therefore I am.
3) then 那么，因而
Run fast, then he won’t catch you.
注意：
a. 两个并列连词不能连用，但therefore, then, yet可以和并列连词连用。 You can watch TV, and or you can go to bed.(错误)
He hurt his leg, and so / and therefore he couldn't play football.(正确)
b. although不与 but连用，但是although可以与yet连用 Although he was ill, but he tried his best to do the work.(错误) Although he was ill, yet he tried his best to do the work.(正确)
连词
连词是一种虚词， 它不能独立担任句子成分而只起连接词与词，短语与短语以及句与句的作用。连词主要可分为两类：并列连词和从属连词。
一．并列连词：用来连接平行的词、词组和分句。
1、and
(1)连接两个并列的谓语：
They sat down and talked about something.
(2)连接两个并列的动词不定式，第二个不定式往往省略to：
They started to dance and sing.
(3)可以和祈使句或名词词组连用表示条件（or也有此用法）：
Make up your mind, and you'll get the chance.
= If you make up your mind, you'll get the chance.
One more effort, and you'll succeed.
= If you make one more effort, you'll succeed
(4)当表示整体或者指同一人时谓语动词用单数, 当and连接的单数名词前分别有each，every，no等词修饰时，谓语也用单数。
The bread and butter is really delicious(美味的).
The mother and teacher is very strict with her son.
No teacher and no student is allowed to smoke in class.
(5)连接两个相同意思的词，表示“渐渐”，或加强语气：
Read it again and again
2、both „and 两者都
Both he and she play the piano.
3、neither„nor 既不„也不„
谓语动词采用就近原则，与nor后的词保持一致。
Neither you nor he is to blame.
4、not only„but (also) 不但„而且„
She plays not only the piano, but (also) the guitar.
*not only„ but also 关联两个分句时，一个分句因有否定词not 而必须倒装。 Not only does he like reading stories, but also he can even write some.
5、as well as 也，与„一样
The teacher, as well as the students, is interested in the activity.
二．表示选择关系
1) or 或者
Which do you prefer, coffee or juice ?
Hurry up, or you'll be late for the class.
2) either„or或者„或者„（谓语动词采用就近原则）
Either you or I am right.
3) or else/ otherwise 否则
Be silent, or else you will be kicked out.
I am tired, otherwise, I would play.
三．表示转折或对比关系
1) but 但是
He is rich but unhappy.
2) while 然而（表示对比意味）
Some people love cats, while others hate them.
3) yet 然而
She said she would be late, yet she arrived on time.
4) however 然而，可是
She does not like him, however, I like him.
5) not„but„ 不是„而是„（not 和but 后面的用词要遵循一致原则） It's not my book, but is his book.
四．表示因果关系
1) for 因为（做并列连词使用时，是在对先行的句子补述原因或者理由，只可以连接句子与句子，通常不置于句首）
He is absent today, for he is ill.
2) so, therefore 因此
He hurt his leg, so he couldn't play in the game.
I think, therefore I am.
3) then 那么，因而
Run fast, then he won’t catch you.
注意：
a. 两个并列连词不能连用，但therefore, then, yet可以和并列连词连用。 You can watch TV, and or you can go to bed.(错误)
He hurt his leg, and so / and therefore he couldn't play football.(正确)
b. although不与 but连用，但是although可以与yet连用 Although he was ill, but he tried his best to do the work.(错误) Although he was ill, yet he tried his best to do the work.(正确)