Unit 1 Cultural relics
語法探究
限制性和非限制性定語從句
定語從句可分為限制性定語從句(Restrictive Attributive Clause)和非限制性定語從句(Non-Restrictive Attributive Clause)，下面將這兩類定語從句作一比較。
一、限制性定語從句
限制性定語從句與先行詞關系密切，對它有限制作用。因此，不可缺少，否則會影響全句的意義。限制性定語從句前一般不用逗號。例如：
There is much that will be unpleasing to the English readers.
有許多東西將會使英國讀者不愉快。
I shall never forget the day when we first met in the park.
我永遠不會忘記我們 在公園相見的那一天。
Is there a shop around where we can get fruit?
附近有可以買到水果的商店嗎？
Do you know the reason why I cam e late?
你知道我遲到的緣故嗎？
“限制”是指概念上的限制，把一般的概念限制為特定的概念。所以，本身已經十分特殊的名詞，如專有名詞、帶有形容詞性物主代詞或是形容詞性指示代詞作限定詞的名詞詞組，其后的定語從句通常都是非限制性的。例如：
Her mother, who had long suffered from arthritis, died last year.
她母親去年去世，此前她長期患有關節(jié)炎。（因mother前有限定詞her，使用非限制性定語從句為宜。）
Charles Smith, who was my former teacher, retired la st year.
查理•史密斯去年退休了，他曾經是我的老師。
This novel, which I have read three times, is very touching.
這本小說很動人，我已經讀了三遍。
在限制性定語從句中，關系代詞如果作賓語，可以省略。例如：
We have got the instrument (that) we need. 我們買到了所需要的儀器。
二、非限制性定語從句
非限制性定語從句與所修飾的名詞（先行詞）關系松馳，只提供有關該名詞的補充情況或附加說明。即使去掉，主句的意思仍然清楚。 書寫時，往往用逗號與主句分開。例如：
Water, which is a clear liquid, has many uses.
水是一種清澈的液體，有許多用途。
Once more I am in Boston, where I have not been for ten years.
我又來到了波士頓，我有十年沒有到這里來了。
非限制性定語從句形式上是從句，其功能實質上相當于一個分句。有時，甚至可以將其譯成狀語從句。例如：
Then he met Mary, who invited him to a party.
后來他遇到了瑪麗，瑪麗邀請他去參加晚會。（who實際上=and she）
When he was seventeen he went to a technical school in Zurich, Switzerland, w here he studied mathematics and physics.
他17歲時，到瑞士蘇黎世一?？茖W校上學，他在那里學習數(shù)學和物理學。(where=and there)
We don’t like the room, which is cold.
我們不喜歡那個房間，它很冷。（which is cold=since it is cold）
He said he was busy, which was untrue.
他說他很忙，其實不然。（which was untrue=though it was untrue）
We need him, wh o knows some English.
我們需要他，他懂些英語。（who knows some English=for he knows some English）
非限制性定語從句中的關系代詞不能省略，that和w hy不可引導非限制性定語從 句。例如：
Wang Xin, whom Lao Li knows well, is our group leader.
王欣是我們的組長，小李對他很了解。（該句中whom不可省略，亦不可為that取代）
which和as引導的非限制性定語從句 可修飾整個主句或主句的一部分，as從句還可置于主句之前。例如：
He has to work on Sundays, which he doesn’t like.
他星期天得工作，這是他不喜歡的。
As you know, the work is very difficult.你們知道，這項工作很難。
which和whom在引導非限制性定語從句時常和of或其他介詞連用。例如：
The buses, most of which were already full, were surrounded by an angry crowd. 公共汽車大部分都已滿載，周圍是一大群憤怒的人。
Her sons, both of whom work abroad, ring her up every week.
她的兩個兒子都在國外工作，每周都給她打電話。
which引導非限制性定語從句有時可作定語。例如：
Tom spent four years in college, during which time he learned French.
湯姆在大學待了四年，在此期間他學了法語。
I may have to go into hospital, in which case I won’t be going on holiday. 我可能得住院，如果那樣我就不去度假了。
As is known to all, the earth goes around the sun.
正如我們所知，地球繞著太陽轉。
as指代后面一句話的內容，這時只能用as,因 為which引導的非限制性定語從句只能置于句末，而as引導的非限制性定語從句既可放在 句末，也可置于句中或句首。如上面的句子還可以寫作：
The earth, as we know, goes around the sun.
此外as在引導非限制性定語從句時，有“正如、似”的含義，所以下列結構中多用as:
as has been said above 如上所述 as anybody can see 正如人人所看到的那樣
as we had expected 正如我們所預料的那樣

［典例解析］
① He was much kinder to his youngest son than to others,______, of course, made the others envy him.
A. who B. that C. what D. which
[解析]本題考查非限制性定語從句，先行詞是前面的整個句子，which所引導的句子對前面主句起補充說明作用。做題時，先排除B.C兩項，因為它不能引導非限制性定語從句，
而A項只能引導先行詞是人的定語從句。
答案：D
② ______is known to everybody, the moon travels around the earth once every month.
A. It B. As C. That D. What
[解析]此題考查定語從句，放在句首只能用as。若選A應為：It is known to everybody
that the moon…
答案：B