定语从句that不能省略
一、定语从句that不能省略情况
1.非限制性定语从句中,that有其他意思不可省
2.有不定代词时
3.有only时
4.有序数词时
5.指人又指物时
6.有形容词最高级时
二、定语从句中关系词的省略与不省略
1.关系代词which,whom,who,that在定语从句中作宾语时可以省略.
Here is the man (who/that/whom)you're been looking for.
以下情况不能省略：
（1）在介词+whom与介词+which中,whom,which不能省略.
Do you know any shops nearby in which I can buy flowers?
That is the headmaster with whom my father was talking just now.
注：当介词放在动词后时,which,whom就可以省略.
Who is the man (whom) you talked with just now?
（2）在非限制性定语从句中,作宾语的关系代词也不能省略.
Mr Green,whom you know,is the tallest in our school.
The elephant is like a spear,as anybody can see.
（3）在the same ...as,such...as,as...as,the same...that中,as,that即使作宾语,也不能省略I have bought the same bicycle as you have (bought).(指同类用as)
This is the same book that I read the day before yesterday.(that指同一个)
（4）当由and,but,or等连词连接两个或两个以上的定语从句修饰一个先行词时,第一个关系代词可省,但第二,第三个不可省略.
This is the book (which) I read yesterday and which I find very interesting.
2.当that在从句中作补语时可以省略.
He is not the man (that) he used to be.
She is all (that) a teacher should be.
3.在there be 结构中出现定语从句,或在定语从句中出现there be 时,用作主语的关系代词也可省略.
There is a man downstairs (who) wants to see you.
This is the best dictionary (that) there is in the library.
4.状语的省略
（1）当先行词是reason,而且定语从句中作原因状语时,关系代词可用why,that,也可以省略.
The reason (why/that) he failed was his laziness.
That is the reason (why) I did it.
（2）当先行词是way,且在定语从句中作方式状语时,关系代词可用in which,that,也可以省略.
The way (in which/that) these comrades look at problems is wrong.
That was the way (in which/that) she worked the problem out.
注意：当关系代词在定语从句中作主语时,不省略.
例如：I don't know the way that/ which leads to the top of the mountains.
(3)当先行词是time时,关系代词可用when,that 或省略.
The second time (that) I saw him was in 1980.
I don't know the exact time (when/that) the sports meet will take place.
注意：关系代词作宾语有时也不能省略.
拓展
1同位语从句
在复合句中用作同位语的从句叫同位语从句，常常跟在fact,idea,opinion,news,hope,belief等名词后面,用以说明该名词表示的具体内容，可以由名词、代词、短语及句子来充当同位语从句。
同位语从句是名词从句,其作用相当于一个名词,对前面抽象名词的进一步的说明和解释。
2定语从句
定语从句是由关系代词和关系副词引导的从句，用来修饰名词或代词，起到定语的作用，所以叫做定语从句。定语从句的作用是作定语修饰主句的某个成分，通常分为限定性和非限定性从句两种。
定语从句不同于单词作定语的情况，它需要放在被修饰的词（即先行词）之后，一般由关系代词来引导，关系代词必须放在定语从句之首。被修饰的词叫先行词，由关系词（关系代词或关系副词）引出。
3同位语从句与定语从句的区别
1、引导同位语从句的that是连词,在从句中不充当任何成份,而引导定语从句的`that是关系代词,除起连接作用外,还在从句中充当主语、宾语或表语等，如：
The idea that computers can recognize human voices surprises many people.
计算机能够识别人的声音的想法使许多人感到惊奇。（同位语从句，that在从句中不充当任何成份）
The idea that he gave surprises many people．他提出的观点令许多人感到吃惊。
（定语从句，that在从句中作gave的宾语）
2、引导词的不同
what,how,if,whatever等可引导名词性从句，但不引导定语从句。
3、同位语从句与前面的名词是同位关系,即说明它前面名词的内容；而定语从句与前面的名词是修饰与被修饰关系,即限定它前面的名词范围,或补充一些情况。如：
The news that l have passed the math exam is true．我通过了数学考试这一消息是真的。
（同位语从句,即从句所表达的意思就是前面名词的内容）
The news that he told me just now is true．他刚才告诉我的消息是真的。
（定语从句,从句对前面名词起修饰限制作用,即“他告诉我的”那个消息,而不是别的消息）
4、定语从句的先行词是名词或代词；而同位语从句的先行词只能是名词，而且仅限于idea，fact，hope，news，doubt，truth，information，suggestion，question，belief，conclusion等少数名词。而且when，where，why引导的定语从句的先行词一定分别是表示时间、地点和原因的名词，而三者引导的同位语从句的先行词则肯定不是表示时间、地点和原因的名词。I have no idea when they will come.我不知道他们什么时候来。(同位语从句)
I’ll never forget the days when I lived there.我永远不会忘记我住在那儿的日子。(定语从句)
