2019高考二輪復習英語教案: 定語從句
3.先行詞與定語從句隔離
定語從句一般緊跟在先行詞之后，但定語從句與先行詞之間有時也會插入別的成分，構成先行詞與定語從句的隔離。例如：
1）this is the article written by him that is poke to you about……
2）he was the only person in this country who was invited
四、as在定語從句中的用法
1. 引導限制性定語從句和非限制性定語從句
（1）as多與such 或the same連用，可以代替先行詞是人或物的名詞。
（2）as 也可單獨使用，引導非限制性定語從句，作用相當于which.例如：
the elephant's nose is like a snake，as anybody can see.
（3）the same--- that與 the same ---as在意思上是不同的。
2.as引導的非限制性定語從句的位置
as引導的非限制性定語從句位置較靈活，可以位于主句前面。中間或后面，一般用逗號與主句隔開，但which所引導的非限制性定語從句只能放在主句之后。例如：
（1）as is expected，the england team won the football match.
（2）the earth runs around the sun，as is known by everyone.
3.as, which的比較
1).在非限制性定語從句中，均可替代整個主句或句中某個部分，在從句中作主語，賓語，表語.如從句在主句之后，兩者皆可用
they failed in the exam, as/which is natural.
she seems a scientist, as/which in fact she is.
grammar is not a set of dead rules, which/as i have said before.
2).如從句在主句之前，用as
as we all know, his parents were killed in this war.
as is known to all, the earth travels around the sun.
3).如關系代詞代表主句全句意思，有“正如...”“就象...”之意時，用as
we won the match, as we had expected.
he agreed to the plan, as was to be expected.
4). 當先行項被the same, such, so修飾時，用as
this is the same book as you bought yesterday.同類書 (比較：this is the
same book that you bought yesterday.同一本書)
don’t believe in such men as praise you to your face.
i never give my students so difficult a question as no one can work
out.
5). 當從句內容對主句內容起消極作用，則用which
the young man cheated his friend out of much money, which was disgraced.
6). as 也可以用來引導非限制性定語從句， 用來指待一件事，這時它的位置可以放在句首、句中和句尾。
he is an american, as/which we know from his accent.
as we know from his accent, he is an american.
he, as we know from his accent, is an american.
as has been said above, grammar is not a set of dead rules.
grammar, as has been said above, is not a set of rules.
grammar is not a set of dead rules, as/which has been said above.
正如: as everyone knows, as you may still remember, as you said, as i
can see, as has been mentioned above, as you may have heard, and etc.