定语从句as的三种用法如下:
(1) as引导的定语从句修饰表人或物的先行词,即先行词可以是人也可以是物;在定语从句中可以做主语、宾语或表语;常用于the sameas/suchas/as(so)as句型,as不论在定语从句中作何成分,均不能省略。
① 先行词为人such teachers, as作主语。
②I’ll buy the same bike as I lost yesterday. 先行词为物the same bike,as作宾语 ,指同一类事物 ※此时注意和the same that 引导的定语从句的区别。
It'that引导定语从句,作宾语,指同一个事物。
She wore the same dress that she wore at Mary's wedding. (the samethat特指同一个) 她穿着她在Mary婚礼上穿过的同一条裙子。 (the sameas 泛指同一类) 她穿着和她妹妹所穿的一样的裙子。 那块手表和我丢失的一模一样。(the sameas 泛指同一类) 那就是我丢失的那块手表。(the samethat特指同一个)
③The school is just the same one as it was 10 years ago.
先行词为物the same one (school), as作表语。
It先行词为物so heavy a box,as作宾语。
此时应注意as引导的定语从句和结果状语从句such / sothat的区分
It结果状语从句sothat如此以至于 He is such a good student as is liked by everyone.(定语从句,as在从句中作主语) (结果状语从句suchthat) that在从句中不充当任何成分,故不是定语从句,而是结果状语从句。