As 作关系代词1.引导限制性定语从句，用在“ such… as”, “the same …as/the same as” 等结构中，常译作“像……一样的人或物”，“凡是……的人或物”。 e.g He wished to be such a man as Lei Feng was.My bike is the same as yours. ①②③2. 引导非限制性定语从句，用来指代它前面的整个句子 ( 即先行句 ) ，意思是“这一点”。这个分句可以放在句首，句中，或句末。 e.gThis elephant is like a snake, as anybody can see.④As is well known, oceans cover more than 70% of the earth.3.若非限制性定语从句位于句首，句中或句末， 则用 as 来引导。 e.g As we expected, he completed his task with great success.①② The compass was invented in China, as we know now.4.若非限制性定语从句中的谓语动词是 be said be known,be expected, be reported , be announced 等结构时，不论是在句首，句中， 句末，都必须 as 用来引导 . e.gAs is known to us, Taiwan is a part of China.as 引导的非限制性定语从句 (1)This is the same pen as I lost.This is the same pen that I lost.Please compare:这本书和我丢的那本一模一样。这本书就是我丢的那本。as 引导的限制性定语从句 (2)This is such an interesting book ____ we all like.This is so interesting a book _____ we all like.This is such an interesting book ____we all like it.This is so interesting a book ____we all like it.asthatPlease complete the following sentences and compare:asthat这是大家都喜欢的如此有趣的一本书。 ( 定语从句 )这本书如此有趣，大家都喜欢。 ( 结果状语从句 )考点五： as 与 which 引导的定语从句 两者均可引导非限制性定语从句，有时可以互换，但下列情况多用 as 。1. 关系代词引导的定语从句居句首时。e.g. As we all know, the earth is round.2. 当与 such 或 the same 连用时，一般用 as 。e.g. Such books as you tell me are interesting. I have the same plan as you.
