6.定语从句表示“对比”或“转折”

这类定语从句在意义上相当于并列连词but或while连接的并列句。

If they were not，they would not be ready to experiment with new forms and to make mistakes，both of which contribute to their increased ability to learn．(人教大纲版高三第67页)

如果不是这样，他们就很可能不会准备去尝试新的形式，不会准备去犯错误，而这两点恰巧对提高他们的学习能力有好处。

There are still many designs for buildings made by famous architects that were never realized．(人教大纲版高二上第99页)

还有很多出自名家之手的建筑设计没做成实物。

此句中的that were never realized有转折之意，相当于but the designs were never realized．

He has two sons，neither of whom looks like him．

他有两个儿子，但是一个也长得不像他。

此句相当于He has two sons，but neither of them looks like him．

Greenland was not a continent，as people thought．

格陵兰岛并不像人们所想象的那样是一个大陆。

此句相当于Greenland was not a continent，but people thought it was．