1.由關系代詞 who， whom ， whose， that ， which；關系副詞 when ，
where ， why引導。

    （下面十個句子請讀5 遍并脫口譯出！）

    e.g.1. The death notices tell us about people who have died during
the week. 2. The man（whom） you spoke to just now is my friend. 3. The
building whose lights are on is beautiful. 4. Please find a place which
we can have a private talk in. 5. The knee is the joint where the thighbone
meets the large bone of the lower leg. 6. He still remembers the day when
he went to school. 7. It is no need telling us the reason why you didn't
finish it in time. 8. He has three sons ， two of whom died in the war.
9. Mr. Smith， whose wife is a clerk， teaches us English. 10. In the
Sunday paper there are comics ， which children enjoy.

    2.只能用that和who 引導的定語從句

    A.all ， nothing， anything ， a few， one做先行詞指物時B.先行詞前
有形容詞最高級修飾時，后面常跟that而不是which C.先行詞前有 the only ，
the first ， the last ， the next ， the very 等詞修飾時，引導詞只能用
that D. 當先行詞是 anyone ， anybody， everyone ， everybody， someone，
somebody時，后面要用who 或whom e.g. All that glitters is not gold.閃光
的并非都是金子。

    3.as引導定語從句

    A.引導限制性語從句。

    在此類定語從句中，as常與主語中作為其先行詞的such， the same 或as聯
用構成，"such …… as"，"the same …… as"和"as ……as" 句型，可代替先
行詞。

    e.g. We hope to get such a tool as he is using. 我們希望得到他正在
用的那種工具。

    B.as引導非限制性定語從句時，作用與which 相同，as作為關系代詞代替整
個主句。

    （這是語法考試的一個考點。）

    注意區別：as引導的從句用于句首、句中或句后，而which 引導的定語從句
不能放在句首。

    e.g. As is reported ， a foreign delegation will visit the city.據
報道，一個外國代表團將訪問這個城市。