例句：The boy believes that he will travel through space to other planets.
注意事项：当主句谓语动词是 think, believe, suppose, expect 等词，而宾语从句的意思是否定时，常把否定转移至主句表示。
例句：I don’t think it is right for him to treat you like that.

2.在以下情况中that不能省略
a.当句中的动词后接多于两个由that引导的宾语从句时，第一个that可省，但后面的that不可省。
例句：He said (that) you were too young to understand the matter and that he was asked not to tell you.
b.当主句的谓语动词与that宾语从句之间有插入语时，that一般不可省。
例句：Just then I noticed, for the first time, that our master was wearing his fine green coat and his black silk cap.
c.当that从句是双宾语中的直接宾语时，that不可省。
例句：I can’t tell him that his mother died.
d.注:许多带复合宾语的句子，that引导的宾语从句经常移到句子后部，而用it作形式宾语。
例句：I find it necessary that we should do the homework on time.

（二）由whether,if 引导的宾语从句
1.由whether(if)引导的宾语从句，实际上是一般疑问句演变而来的。意思是“是否”。宾语从句要用陈述句语序。
一般说来，在宾语从句中whether与if可以互换使用，但在特殊情况下if与whether是不能互换的。
例句：I wonder whether(if) they will come to our party.

2.只能用whether，不能用if引导的宾语从句
a.在带to的不定式前
例句：We decided whether to walk there.
b.在介词的后面
例句：I’m thinking of whether we should go to see the film.
c.在动词后面的宾语从句时
例句：We discussed whether we had a sports meeting next week
d.直接与or not连用时
例句：I can’t say whether or not thet can come on time.

3.只能用if不能用whether引导的宾语从句
a.if引导条件状语从句，意为“如果”
例句：The students will go on a picnic if it is sunny.
b.if引导否定概念的宾语从句时
例句：He asked if I didn’t come to school yesterday.
c.引导状语从句even if（即使）和as if（好象）时
例句：He talks as if he has known all about it.

if,whether在宾语从句中的区别
a.if和whether在作“是否”解时,引导宾语从句常放在动词know,ask,care,wonder,find out等之后,介词后一般不用if
b.少数动词,如:leave,put,discuss,doubt后的宾语从句常用whether. 
c. whether后可以加or not,但是if不可以.
d.在不定式前只能用whether.
（如：I can’t decide whether to stay. 我不能决定是否留下。）
e.避免歧异时,我们常用whether而不用if.

（三）连接代词和连接副词引导的宾语从句
这样的宾语从句实际上是由特殊疑问句变化而来的，宾语从句要用陈述句语序。
用于这种结构的动词常常是：see, say, tell, ask, answer, know, decide, show, find out, imagine, suggest, doubt, wonder, discover, understand, inform, advise等。
1.英语中的连接代词有：who,whom,whose,which,what,在句中担任主语、宾语、定语或者表语。
例句：Can you tell me whom you are waiting for?
2.英语中的连接副词有：when,where,why,how，在句中担任状语的成分。
例句：None of us knows where these new parts can be bought.

简化宾语从句常用六法：
方法一：
当主句谓语动词是hope， decide， wish， choose， agree， promise等，
且宾语从句的主语与主句主语一致时，宾语从句可简化为不定式结构。
例如：
Li Ming hopes he will be back very soon.
→Li Ming hopes to be back very soon.
We decided that we would help him.
→We decided to help him.

方法二：当主句谓语动词是know， learn， remember， forget， tell等动词，
且主句主语与从句主语一致时，宾语从句可简化为“疑问词+不定式”结构。例如：
She has forgotten how she can open the window.
→She has forgotten how to open the window.
注：当主句谓语动词是tell， ask， show， teach等动词，
且后带双宾语，从句主语和间接宾语一致时，宾语从句可简化为“疑问词+不定式”结构。例如：
Could you tell me how I can get to the station？
→Could you tell me how to get to the station？

方法三：当主句的谓语动词是order（命令），require（需要）等时，
如果主句和从句的主语不一致，宾语从句可简化为“名词（代词）+不定式”结构。例如：
The headmaster ordered that we should start at once.
→ The headmaster ordered us to start at once.

方法四：某些动词后的宾语从句，可以用介词加动名词（短语）等其他形式简化。例如：
He insisted that he should go with us.
→He insisted on going with us.
The poor boy doesn’t know when and where he was born.
→The poor boy doesn’t know the time and the place of his birth.

方法五：某些动词后面的宾语从句可转化为“宾语+V-ing形式（作宾语补足语）”结构。例如：
Liu Ping found that there was a wallet lying on the ground.
→ Liu Ping found a wallet lying on the ground.

方法六：动词seem后的宾语从句，也可以用不定式（短语）来简化，但句型需要进行适当的变化。例如：
It seemed that the boys were going to win.
→The boys seemed to win.
除上述方法外，还有一些特殊句式的转化。例如：
I found that it was difficult to learn English well.
→I found it difficult to learn English well.
Soon we found that the ground was covered with thick snow.
→Soon we found the ground covered with thick snow.
They found that the box was very heavy.
→They found the box very heavy

 

考点名称：定语从句

• 定语从句：
  担任定语动能的句子称为定语从句。定语从句在句中的作用相当于形容词，故又称为形容词性从句。
  定语从句所修饰的词叫先行词；定语从句一般用关系代词或关系副词来引导，关系词放在先行词与定语之间起连接作用，同时又作从句中的一部分。

• 定语从句的分类：
  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。
  1．由that引导的定语从句
  一般情况下that可指人或物，可以代替who，whom和which，在从句中作主语或谓语动词的宾语，但不能作介词的宾语。如：
  The comrade that（who）is speaking at the meeting is an advanced worker．
  正在会上讲话的那个同志是个先进工人。
  Is this the doctor that（whom）you talked about yesterday？
  这就是你们昨天谈论的那位医生吗？
  The letter that（which）I received yesterday was from my father．
  昨天我收到的信是我父亲寄来的。
  2．由who，whom和whose引导的定语从句
  who在从句中作主语，whom在从句中作宾语，whose在从句中作定语。如：
  This is the thief who stole my bike．这就是偷我自行车的那个贼。
  He is the boy whom you wanted to find．他就是你想要找的那个男孩。
  The girl whose mother is a doctor is waiting for you outside．妈妈是个医生的那个女孩在外面等你。
  3．由which引导的定语从句
  which指物，在从句中作主语或谓语动词的宾语。如：
  The book which Mum bought me last week is called“Red Star Over China”．
  妈妈上周买给我的那本书名叫《西行漫记》。
  The house which Lu Xun once lived in is now the Lu Xun Museum．
  鲁迅曾经住过的那所房子现在是鲁迅博物馆。
  4．由where，when和why引导的定语从句
  where在从句中作地点状语，when在从句中作时间状语，why在从句中作原因状语。如：
  I will never forget the day when I joined the League．我永远忘不了我入团的那一天。
  He will go back to the school where he studied next week．下周他要回到他曾经学习过的学校。
  I don't know the reason why he quarreled with Zhang Lin．我不知道他同张琳吵架的原因。
  ［注意点］
  关系代词在定语从句中作宾语时，关系代词常省去。如：
  The play（which）I watched just now had been on twice on Channel
  我刚才看的那个戏剧在3频道上已上演了两次。

• 限定性定语从句：
  1. that即可代表事物也可代表人，which代表事物；
  它们在从句中作主语或宾语，that在从句中作宾语时常可省略关系词，which在从句中作宾语则不能省略。
  而且，如果which在从句中作“不及物动词＋介词”的介词的宾语，注意介词不要丢掉，而且介词总是放在关系代词which的前边，但有的则放在它原来的位置
  2. which作宾语时，根据先行词与定语从句之间的语义关系，先行词与which之间的介词不能丢