放在主句后面作非限制定語從句時(前面一般加"，"號)，"when"一般譯為"此時"，"那時", 例如：
The meeting will be put off until next month, when we will have made all the preparations. (會議將推遲到下月，那時一切就準(zhǔn)備就緒了。)
另一個關(guān)系副詞是why，由于它固定與the reason搭配, 即： the reason why，不難理解，一般也不作為考試的重點。例如：
This is the reason why the electronic computer cannot entirely replace man. 這就是(為什么)電子計算機(jī)不能完全代替人的原因。
whose (= of which / whom)：做先行詞(不管是人還是物)的定語，漢語為"…的"，不要考慮是否是限制性或非限制性定語從句, 例如：
Pay attention to that boy whose temperature is very high. (理論上也可以寫成：Pay attention to that boy the temperature of whom is very high. 注意那個男孩，他的體溫很高。(非限制性) / 注意那個體溫很高的男孩。(限制性)
介詞 + which (whom)
先看兩個句子：
This is the house. He has lived in the house for over 30 years.
變?yōu)椤ㄕZ從句
This is the house in which he has lived for over 30 years.
上述句子中，先行詞在從句中充當(dāng)介詞賓語，形成"介詞 + which / whom"的形式，考試時要求作出1)要不要介詞;2)若要，使用什么介詞的判斷。由于英語中介詞搭配多為習(xí)慣用法，沒有多少規(guī)律可循，因此這是定語從句考試的一個難點。
記住四個字：瞻前顧后
瞻前：先看看先行詞一般與什么介詞搭配，例如：
There are occasions _____ which joking is not permissible.
→ Joking is not permissible _____ (certain) occasions.
常與occasion搭配的介詞是什么?on，即：
Joking is not permissible on (certain) occasions. (有的場合是不容許開玩笑的。)
↓
There are occasions on which joking is not permissible.
顧后：看看謂語動詞常與什么介詞搭配，例如：
This car, ____ which I paid a lot of money, is now out of date.
→ I paid a lot of money ______ this car.
Pay (money) for something 是一個固定的搭配，因此應(yīng)填介詞 "for"
當(dāng)A、B、C、D中出現(xiàn) " 介詞 + which / whom" 選項時，而你又確實看不懂時，應(yīng)傾向于選擇" 介詞 + which / whom"的形式，例如：
The two elements _____ water is made are the gases oxygen and hydrogen.
A. that
B. which
C. with which
D. of which
傾向選擇C、D;正確答案D，"be made of "(由…組成):
The two elements are gases (oxygen and hydrogen).
Water is made of the two elements.
兩個句子一合并，便是該句選擇。
(四)其他應(yīng)注意的確問題：
(1) 同位語從句只能用"that"連接
常見的同位語先行詞有：fact(事實), possibility(可能), idea(想法), belief(相信), doubt(疑問), news(消息), order(命令), promise(承諾), evidence(證據(jù)), suggestion(建議)等，例如：
Is there any possibility that all the villagers can send their children to school?(有沒有這種可能，所有村民都能送他們的孩子上學(xué)?)
There can be no doubt that he is a qualified doctor.(毫無疑問，他是個合格的醫(yī)生。)
(2) "as" 也可以做關(guān)系代詞用于連接定語從句，特別是在"such…as…", "the same as…" 以及"正如…"的結(jié)構(gòu)中，例如：
I have never seen a thing as he described. (我從未見過他所描述的那種事。)
As was expected, the performance was a great success. (正如所料，演出獲得了巨大成功。)
把該句理解為：The performance was a great success, which was expected，就比較容易理解as的這種用法。
將定語從句的連接用三句話歸納一下：
↗ 人用who / whom
(1)先行詞在從句中當(dāng)主、賓、表語 →定語用whose
↘ 物用that (= which)/ 非限制用which
↗地點狀語用：where
(2)先行詞在從句中當(dāng) →原因狀語(reason)用：why
↘ 時間狀語用：when
(3)介詞 + which / whom結(jié)構(gòu)：瞻前顧后
