表示转折关系的连词：主要有but, only, while, when, whereas等。
如A great deal has been accomplished, but more remains to be done.
He is riding, while his father is walking in the dust.
Why did you borrow the book when you had one?
He is ill, whereas I am only a little tired.
only表示意义转折，只见于非正式文体。如You may go, only come back early.(only = but)
温馨提示：1 有些词或短语在句中也表示转折意义，如still, yet, however, all the same, after all等。通常作连接性状语。
如The problem was a little hard, yet I was able to work it out
I explained twice, still he couldn’t understand.
如I love strong tea while my father loves coffee.
3 both … and … not结构和neither … nor …的区别在于前者表示部分否定，而后者表示全部否定。如Both you and I are not correct. Neither you nor I am right.