1)or意思为或则。
Which do you prefer,tea,coffee,or juice?
2)eitheror意思为或者或者。注意谓语动词使用就近原则。
Either you or I am right.
3)or else/otherwise不然
Be silent,or else you will be kicked out.
I am tired,otherwise,I would play.
第三类表示转折或对比关系的连词
1)but但He is rich but unhappy.
while然而，表示对比意味Some people love cats,while others hate them.
yet然而She said she would be late,yet she arrived on time.
however然而，可是，不过She does not like him,however,I like him.
2)notbut意思为不是而是
not和but后面的用词要遵循一致原则。
They were not the bones of an animal,but(the bones)of a human being.
第四类表因果关系的连词
1)for由于，做并列连词用时，是在对先行的句子补述缘由或者理由，只可以连接句子与句子，一般不置于句首。
He is absent today,for he is ill.
2)so,therefore因此
He hurt his leg,so he couldnt play in the game.
I think,therefore I am
3)then那样，因而
Hide behind the wall,then they wont see you.
注意：
a.两个并列连词不可以连用，但therefore,then,yet.可以和并列连词连用。
You can watch TV,and or you can go to bed.
He hurt his leg,and so/and therefore he couldnt play in the game.
b.althoughyet，但although不与but连用。
(错)Although he was weak,but he tried his best to do the work..
(对)Although he was weak,yet he tried his best to do the work.
