根据定语从句与先行词的关系，定语从句可分为限制性定语从句及非限制性定语从句。限制性定语从句紧跟先行词，主句与从句不用逗号分开，从句不可省去；非限制性定语从句主句与从句之间有逗号分开，起补充说明作用，如省去，意思仍完整。这次为您整理了非限制性定语从句逗号通用2篇，您的肯定与分享是对小编最大的鼓励。
非限制性定语从句：
即非限定性定语从句，起补充说明作用，缺少也不会影响全句的理解，在非限定性定语从句的前面往往有逗号隔开，如若将非限定性定语从句放在句子中间，其前后都需要用逗号隔开。由as, which 引导的非限定性定语从句，as和which可代整个主句，相当于and this或and that。As一般放在句首，which在句中。
使用规则及注意事项：
1、which引导的非限定性定语从句是用来说明前面整个句子的情况或主句的某一部分。
2、as有时也可用作关系代词 。
as引导非限制性定语从句，若as在从句中作主语，其引导的句子可以放在句首，也可以放在句中。但which引导的非限制性定语从句只能放句中。
例句：
As is reported in the newspaper, some artistic treasures （艺术珍品） will be on show at the exhibition on the weekend.
3、在非限定性定语从句中，关系词不能用that。
限制性定语从句和非限制性定语从句有四大区别：
1在句中作用不同
限制性定语从句对被修饰的先行词有限定制约作用，使该词的含义更具体，更明确。限制性定语从句不能被省略，否则句意就不完整。
非限制性定语从句与先行词关系不十分密切，只是对其作一些附加说明，不起限定制约作用。
如果将非限制性定语从句省去，主句的意义仍然完整。
2外在表现形式不同
限制性定语从句因与先行词关系密切，所以不可以用逗号将其与主句隔开；而非限制性定语从句与先行词关系不十分密切，所以可用逗号将其与主句隔开。
例1.
Do you remember the girl who taught us English?
你还记得教我们英语的那个女孩吗？
例2.
Clock is a kind of instrument which can tell people time.
钟是一种能够告诉人们时间的仪器。
例3.
This is the place where he used to live.
这就是他过去居住的地方。
例4.
Mr. Zhang, who came to see me yesterday, is an old friend of mine.
张先生昨天来看我，他是我的一位朋友。
例5.
We walked down the village street， where they were having market day.
我们沿着村里的大街向前走去，村民们正在那里赶集。
析：在前三个例句中，定语从句与先行词关系密切，为限制性定语从句，不可用逗号将其与主句隔开。在后两个例句中，定语从句与先行词关系不密切，为非限制性定语从句，可用逗号将其与主句隔开。
3先行词内容有所不同
大多数限制性和非限制性定语从句的先行词往往为某一个词或短语，而特殊情况下非限制性定语从句的先行词也可为整个主句，此时非限制性定语从句常由 which 引导。
例 1.
A middle-aged woman killed her husband, which frightened me very much.
一个中年女子杀害了自己的丈夫，这令我十分恐惧。
析：由语境可知，令“我”恐惧的内容应为“中年女子杀害了自己的丈夫”这整个一件事，因此先行词为整个主句，此时应由 which 引导定语从句。
例 2.
A five-year-old boy can speak two foreign languages, which surprises all the people present.
一个五岁男孩会讲两门外语，这令所有在场的人感到非常惊讶。
析：由语境可知，令所有在场的人感到惊讶的内容是“一个五岁男孩会讲两门外语”这整个一件事，因此先行词为整个主句，此时应由 which 引导非限制性定语从句。
4关系词的使用情况有所不同
①that 不可用于引导非限制性定语从句所有关系代词和关系副词均可引导限制性定语从句，大多数关系代词和关系副词可引导非限制性定语从句，但that不可。
例 1.
他送给他母亲一台彩电作为生日礼物，这使她非常高兴。
误：He gave his mother a color TV set for her birthday, that pleased her a lot.
正：He gave his mother a color TV set for her birthday, which pleased her a lot.
例 2.
他没通过这次考试，令我很失望。
误： He didn't pass the exam， that disappointed me.
正： He didn't pass the exam， which disappointed me.
值得注意的是，不少同学误认为只有 which 才能引导非限制性定语从句，这个观点是不正确的。
使用非限制性定语从句时，如果先行词指人，则用 who ，whose 引导非限制性定语从句；先行词指物可用 which 引导非限制性定语从句；先行词表时间或地点且在从句中作时间状语或地点状语时，可用 when ， where 引导非限制性定语从句。
例1.
We'll graduate in July, when we will be free.
我们将于七月份毕业，到那时我们就自由了。
例 2.
Last Sunday they reached Nanjing, where a conference was to be held.
他们上周日到达南京，有个会议要在那里举行。
②关系代词替代情况不同
关系代词 whom 在限制性定语从句中作宾语时可用 who 代替 whom ，但 whom 在非限制性定语从句中作宾语时不可用 who 来代替。
例 1.
This is the girl whom I met in the street.这是我在街上遇到的那个女孩。
析：先行词 the girl 在限制性定语从句中作宾语，可用 who 代替 whom.
例 2.
A young man had a new girl friend, whom he wanted to impress.
一个年轻的小伙子新交了一个女朋友，他想给她留下深刻的印象。
析：先行词 a new girl friend 在非限制性定语从句中作宾语，不可用 who 代替 whom.
在限制性定语从句中，先行词指人时可用 that 代替 who/ whom ，但在非限制性定语从句中先行词指人时，不可用 that 代替 who/whom 。
例：她有一个姐姐，她是教师。
误：She has a sister, that is a teacher.
正：She has a sister, who is teacher.
③关系代词省略情况不同
关系代词在限制性定语从句中作宾语时可以省去，非限制性定语从句的所有关系词均不可省。
例 1.
This is the book (which/that) he lost yesterday.
这就是他昨天丢的那本书。
析： 先行词 the book 在限制性定语从句中作宾语，关系代词 which 或 that 可以省略。
例 2.
The book, which he lost yesterday， has been found.
他昨天丢了这本书，但现在已找到了。
析：先行词 the book 在非限制性定语从句中作宾语，关系代词 which 不可省。
延伸阅读：非限制定语从句的考点
考点一：和限制性定语从句的比较。
区别1：形式不同
限定性定语从句和主句之间不用逗号隔开，而非限定性定语从句与主句之间通常有逗号隔开。
区别2：功能不同
限定性定从对先行词进行修饰、限制和识别，如果去掉，就会造成句意不完整或概念不清；
非限定性定从对先行词补充说明，如果省略，句意仍然清楚、完整。
People who take physical exercise live longer.
His daughter, who is in Boston now, is coming home next week.
区别3：翻译不同
限定性定语从句翻译在它所修饰的先行词之前；非限定性定语从句与主句分开。
He is the man whose car was stolen.
他就是汽车被窃的那个人。
I’ve invited Jim, who lives in the next flat.
我邀请了吉姆，他就住在隔壁。
区别4：含义不同
I have a sister who is a doctor.
我有一个当医生的姐姐。（姐姐不止一个）
I have a sister, who is a doctor.
我有一个姐姐，她是当医生的。（只有一个姐姐）
区别5：先行词不同
限定性定从的先行词只能是名词或代词；
非限定性定从的先行词则可以是名词或代词，
也可以是短语或主句。
Peter drove too fast, which was dangerous.
彼得开车很快，这是很危险的。
(which指drive too fast)
He changed his mind, which made me very angry.
他改变了主意，这使我很生气。
（which指整个主句）
区别6：关系词不同
that和why不能引导非限制性定从；
在非限制性定从中，关系词一律不省略。
考点二：as引导非限定性定语从句， 指代主句整个句子，可以放在主句之前， 译为“正如”。
As we all know, he studies very hard.
As is known to all, he is the best student in our class.
考点三：引导词前的介词
So far only two people have seen this house,
of whom neither wants to buy it.
So far only two people have seen this house,
neither of whom wants to buy it.
一、限制性定语从句
1、关系代词that既可代表事物也可代表人，which只代表事物，它们在从句
中作主语或宾语。在从句中作宾语时常可省略。
I was the only person in our office that was invited to the palace ball．
The present that（which）I received last week was from my sister．
This is a book which is about space rocket technology．
2、关系代词who和whom引导的从句用来修饰人，分别作从句中的主语和宾语，whom作宾语时，要注意它可以作动词的宾语也可以作介词的宾语。如：
This is the man who helped me．
The doctor whom you are looking for is in the room．
3、 whose是关系代词，修饰名词，作定语，相当于who和whom的所有格，既可以修饰人又可以修饰物。如：
Do you know the student whose name is Wang Fei？
We lived in a room whose window opens to the west.
4、 where是关系副词，用来引导表示地点的定语从句，where在从句中作状语。如：
At last we arrived at a small village where we’ll work for a week.
5、 when是关系副词，引导定语从句表示时间，在从句中作状语。
注意，表示时间的the time，the day, the moment作先行词，其定语从句引导词有四种情况：1）when,2) in/ on which3) that4)省略。如：
By the time you arrive in London, we will have stayed there for two weeks.
I still remember the day I met her.
Each time he goes to business trip, he brings a lot of living necessities.
6、 why是关系副词，引导定语从句表示原因，在从句中作状语。
7、关系副词when, where, why可以用“介词+关系代词”结构代替，但有两点要注意：
1）在“介词+关系代词”结构中，不能用that。关系代词指物用which,指人时用whom，不用who；且which和whom在这个结构中不能省略。如：
The plane in which we flew to[] Canada is very comfortable. （正确）
The plane in that we flew in to Canada is very comfortable.（错误）
2）在使用介词+关系代词引导的定语从句时，含有介词的动词短语一般不拆开使用，如：look for, look after, take care of等。如“This is the watch which/that I am looking for.”不可以改为“This is the watch for which I am looking.”
二、非限制性定语从句
非限制性定语从句的作用是对所修饰的成分作进一步说明，通常和主句间用逗号隔开，将从句拿掉后其他部分仍可成立
1、 which引导的非限定性定语从句，可用来说明前面整个句子的情况或主句的某一部分。如：
She heard a terrible noise，which brought her heart into her mouth．
David studies hard and is ready to help others，which is what his parents expect．
2、在非限制性定语从句中，不能用that，而用who, whom代表人，用which或as代表事物。关系代词作定语时用whose。如：
He loved his parents deeply, both of whom are very kind to him.
In the basket there are quite many apples, which have gone bad.
There are forty students in our class in all, most of whom are from big cities.限
His mother, who loves him very much, is strict with him.
China, which was founded in 1949, is becoming more and more powerful.
限制性定语从句和非限制性定语从句有时表达的'意义不同，试分析下面两个句子的差别：
His brother who is now a doctor always encourages him to go to college.
他那当医生的哥哥常鼓励他要考上大学。（他还有其他的哥哥）
His brother, who is now a doctor, always encourages him to go to college.
他的哥哥是当医生的，常鼓励他要考上大学。（他只有一个哥哥）
3、 as和which引导非限制性定语从句
as和which引导非限制性定语从句，有相同之处也有不同之处。具体情况是：
1）As和which都可以在定语从句中做主语或者宾语，代表前面整个句子。
He married her, as/which was natural.
He was honest, as/which we can see.
As we know, smoking is harmful to one's health. The sun heats the earth, which is very important to us.
As we know, smoking is harmful to one’s health.
As is know, smoking is harmful to one’s health.
2）as引导非限制性定语从句，可放在主句之前，或者主句之后，甚至可以
切割一个主句；which引导的非限制性定语从句只能放在主句之后。
As is known to all, China is a developing country.
He is from the south, as we can see from his accent.
John, as you know, is a famous writer.
He has been to Paris more than several times, which I don’t believe.注意：当主句和从句存在逻辑上的因果关系时，常用which
Tom was always late for school, which made his teacher angry.
3）the same… as；such…as是固定结构，意思是“和……一样……。”如：
I have got into the same trouble as he (has)。
I have never heard such a story as he tells.
He is not such a fool as he looks.
This is the same book as I lost last week.
注意：当先行次由the same修饰时，偶尔也用that引导定语从句，但是和由as所引导的定语从句意思不同。如：
She wore the same dress that she wore at Mary’s wedding.
她穿着她在玛丽婚礼上穿过的一条裙子。
She wore the same dress as her young sister wore.
她穿着和她妹妹所穿的一样的裙子。
语法专项练习
单项填空
1、 The soldier ran to the building, and ____flew a flag.
A. on the top of whichB. on the top of whom
C. on the top of itD. which
2、 When the same man ____murdered the old lady entered the hotel once more,
the waiter immediately phoned the police.
A. asB. thatC. whichD. whom
3、 He wore, ____was very common at the time, a black jacket.
A. thatB. whichC. itD. what
4、 Was it in the room ____Mr. Johnson lived ____the exhibition was held?
A. that; thatB. where; thatC. where; whereD. that; where
5、 ____, the population of China is the largest in the world.
A. It is known thatB. As is well known
C. Which is well knownD. We all know that
6、 This is the very reason____ he gave me.
A. thatB. whyC. for whichD. which
7、 He arrived in New York in 1949, ____, some time later, he became a writer.
A. whenB. whereC. thatD. which
8、 They’re talking about the newly opened market, ____you get all ____you need.
A. in which; whichB. where; thatC. where; whichD. which; that
9、 She heard a terrible noise, ____brought her heart into her mouth.
A. itB. whichC. thisD. that
10、 I said nothing, ____made her angry.
A. whichB. whatC. /D. that
11、 I shall never forget the time ____the blacks and whites were fighting side by side.
A. whenB. thatC. /D. A, B and C
12、 He has three sons, ____are doctors.
A. two of whomB. both of whomC. all of themD. each of them
13、 He tore up my photo, and____ made me angry.
A. thatB. whatC. whichD. who
14、 I still remember the sitting-room____ my mother and I sat in last year.
A. whereB. in whichC. thatD. to which
15、 The day we looked forward to ____.
A. comeB. comingC. having comeD. has come
答案
1、 C。由于and的存在，这是并列句，而不是非限制性定语从句，排除A.
2、 B。这里the same修饰man，其后只能用能代表人的关系代词that引导定语从句；whom是宾格，这里引导词要在从句中作主语，故不能用。
3、 B。which引导一个非限制性定语从句，which所代表的是整个主句的意思，为了强调从句而提前了。
4、 B。识别强调句型不难，但极有可能在第一个空填that,而误选D。其实被强调的部分还含有一个定语从句，修饰room.
5、 B。只有as引导的非限制性定语从句可位于主句之前，排除C；若去掉句中的逗号，A项则可构成含有主语从句的复合句，D项则可构成含有宾语从句的复合句。
6、 A。强干扰项是B.这里不选why，是因为定语从句缺的是宾语，故用关系代词that.试比较：This is the reason why he gave me so much money;先行词已被very一类的词修饰过了，其后定语从句不用which引导，故亦排除D.
7、 B。强干扰项是A.想当然地认为定语从句先行词是时间，事实上，这个非限制性定语从句所修饰的先行词是地点New York,被介词结构分隔了。
8、 B。where引导非限制性定语从句，在该定语从句中，不定代词all又带that引导的限制性定语从句。
9、 B。从句子结构看，这是个主从复合句，故不用it和this;引导非限制性定语从句不用that.
10、 A。如果只想当然地认为nothing是不定代词，其后的定语从句要用that引导，就错了。这里是一个非限制性定语从句，应该用which引导，并且which所代表的是整个主句的意思。
11、 D。英语中少数几个与时间有关的名词，如the time, the day, the moment作先行词，所带定语从句的引导词可用that代替when,也可以省略。
12、 A。如果看出这是个定语从句，C、D很容易排除。Both of whom中的whom指两个，数量是2/2；two of whom, whom指三人，数量是2/3.
13、 A。强干扰项是C,因为有and，这是并列句，不是非限制性定语从句。这里that是指示代词，作主语。
14、 C。如果错误地把后面的介词in理解为in last year,可能误选A、B.事实上，in与前边的关系代词that引导定语从句。Last year是名词词组作时间状语，不加冠词。
15、 D。这里“(that/which) we looked forward to”是修饰the day的定语从句；to的宾语是省略了的引导词。