the same...as...表示"与……同样的",不是同一个 the same...that..表示"同一个",就是那个 例如：This is the same pen as I lost last week.这同我上周丢失的那支钢笔一样.(但不是同一支) This is the same pen that I lost last week.这就是我上周丢失的那支钢笔.the same后面可以接定语从句,如果后面的定语从句是省略的情况,则用as来引导,即the same...as； 如果是完整的定语从句,须根据不同的先行词来确定用 that,when,where,when,who等.例如:He studies in the same school as I.他和我在同一所学校里上学.He was born in the same hospital where my brother was born.他和我哥哥在同一家医院里出生.The young teacher is the same man who visited our school last year.那个青年教师就是去年来我校参观的那个人.
关于定于从句,我们对that/which/who/ whose/when /where.等引导词引导的都比较熟悉,而as则有些模糊.下面我就详细得把as定语从句的用法及其与其他定语从句的区别说一下.
"As”可以用作关系代词引导定语从句.
一：as可以代替整个句子或一件事,引导非限制性定语从句,在从句中作主语、宾语或表语,意为“正如……,就像……,据……”；从句位置可置于主句之前或之后,有时也可作为插入语置于句中,一般用逗号和主句隔开.
as的这种用法常见于以下这些结构:as we can see,as can be seen,as we know,as is（well） known,as may be imagined,as often happens,as has been said before,as was mentioned above,as is often the case,as/indeed it is,etc.
多看一些例句:As is well known,great changes have taken place in China.or:Great changes,as is well known,have taken place in China.众所周知,中国发生了巨大的变化.( as在定语从句中作主语.)
This experiment is very simple,as indeed it is.实验非常简单,事实上也确实如此.(as在定语从句中作表语.)
注意：① which在引导非限制性定语从句时,也有和as一样的功能,可以代替整个句子,但which只能用在主句之后.
②在as所引导的非限制性定语从句中,如果运用的是被动语态结构,be动词可以省略；但which没有此用法,be动词不可省.例如:She married him,which was unexpected.＝She married him as（was） unexpected.她嫁给了她,这一点大家都没有料到.（作主语,代替前面的句子；用which时was不可省.）
二 as除了代替整个句子,也可以代替主句中一个特定的词.as在它引导的定语从句（限制性或非限制性）中可以充当主语,宾语和表语；在这种用法中它经常和such,so,the same等词搭配使用；且当先行词中有such,so,the same等词修饰时,关系代词通常必须用as.
例如:1.They were satisfied with this decision,as was agreed beforehand.他们对这个决定都满意,这事先已经经过他们同意了.( as在定语从句中作主语,其先行词是this decision)
2.I never heard such stories as he tells.我从未听过他讲的这类故事.( as在定语从句中作宾语,先行词是such stories.)
3.The place doesn't look the same as it was before liberation.这个地方看上一去和解放前大不一样了.( as在定语从句中作表语,先行词是same)
4.Have you bought the same book as I referred to yesterday?你有没有买我昨天说的那本书啊?( as在定语从句中作宾语,先行词是book)
注意:先行词中有the same修饰时,定语从句也可用that引导,但意思上有区别,as表示与此同类； that表示就是那一个,同物.
例如:Have you brought the same book that I gave you yesterday?
你有没有把我昨天给你的那本书带来啊?( that在定语从句中作宾语,先行词是book.体会：本句中所指的书是同一本,上句中指的是同一类书,而并不就是那一本.)
