一.宾语从句的定义
置于动词、介词等词性后面起宾语作用的从句叫宾语从句。谓语动词、介词、动词不定式，v.-ing形式后面都能带宾语从句。有些形容词（afraid,sure,glad等）之后也可以带宾语从句。
二.宾语从句中引导词的用法
在复合句中作主句的宾语，引导词有：
连词：that (that 常可省略),whether, if
代词：who, whose, what ,which
副词：when ,where, how, why 等。
（一）that引导的宾语从句（在非正式场合that可以省略）
1. 可跟that从句做宾语的动词有：
say, think, insist, wish, hope, demand, imagine, wonder, know, suppose, see, believe, agree, admit, deny, expect, explain, order, command, feel, dream, suggest, hear, mean, notice, prefer, request, require, propose, declare, report等。
例句：The boy believes that he will travel through space to other planets.
2.引导宾语从句的that在下列情况下一般不省略：
（1）. 宾语从句前有插入语。如：
We hope, on the contrary, that he will stay at home with us. 恰恰相反，我们希望他和我们呆在家里。
（2）. 有间接宾语时。如：
He told me that he was leaving for Japan. 他告诉我他要去日本。
（3）. that在与之并列的另一个宾语从句之后。如：
He said (that) the book was very interesting and that(不省略) all the children like to read it.他说那本书很有趣，所有小孩都喜欢读。
（4）. 在“it(形式宾语)+补语”之后时。如：
I think it necessary that he should stay here. 我们认为他有必要留在这里。
（5）. that从句单独回答问题时。如：
—What did he hear? 他听说了什么事？
—That Kate had passed the exam. (他听说)凯特考试及格了。
（6）. 在except等介词后。如：
He has no special fault except that he smokes too much.他除了抽烟太多之外,没有什么特别的毛病。
（7）. 位于句首时。如：
That our team will win, I believe. 我相信我们队会赢。
（8）. 在较为正式或不常用的动词(如reply, object)后。如：
He replied that he disagreed. 他回答说他不同意。
（二）由whether,if 引导的宾语从句
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。
1.只能用whether，不能用if引导的宾语从句
（1）在带to的不定式前
例句：We decided whether to walk there.
（2）在介词的后面
例句：I’m thinking of whether we should go to see the film.
（3）在动词discuss后面的宾语从句时
例句：We discussed whether we had a sports meeting next week
（4）直接与or not连用时
例句：I can’t say whether or not that can come on time.
2.只能用if不能用whether引导的宾语从句
（1）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.
（2）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.
（3）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.
（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。
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?
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.
三.宾语从句的语序
宾语从句的语序是陈述句语序即：连接代词/副词+主语+谓语+其他成分。例句如下：
I don’t know what they are looking for.
Could you tell me when the train will leave?
Can you imagine what kind of man he is?
四.宾语从句的时态
主句是一般现在时，从句根据实际情况使用任何时态。
例句：The headmaster hopes everything goes well.
主句是过去时态，从句须用过去时态的某种形式。
例句：She was sorry that she hadn’t finished her work on time.
当宾语从句表示的是一个客观真理或者事实时，即使主句是过去时，从句也用一般现在时态。
例句：The teacher told his class that light travels faster than sound.
五 宾语从句中的否定前移
如果主句的谓语动词是believe, think, guess, suppose等，而且主句的主语又是第一人称时，它后面接的宾语从句的否定词通常要前移到主句中，即否定主句中的动词，这也就是我们平常所说的“否定的转移”。
I don't think (that) it will rain.
I don't believe he tells lies.
注意：
① 这种否定前移的宾语从句，在变成反意疑问句时，反意疑问句的主谓语要与从句一致。
I don't think (that) he is interested in that thing, is he? 我认为他对那件事不感兴趣，对吗？
② 如果主句的主语是第二和第三人称时，它后面接的宾语从句的否定词通常不前移，它的反意疑问句的主谓语应该与主句一致，即如果主句是肯定，反意疑问部分就用否定；如果主句是否定，那么反意疑问部分就用肯定。
She thought that film was not interesting, didn't she? 她认为那部电影不好看，是吗？
You think you can't get up, don't you? 你认为你起不来，是吗？
六 宾语从句的简化（常用六法 ）
方法一：简化为不定式结构
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：简化为“疑问词+不定式”
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：简化为“名词（代词）+不定式”
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：简化为介词加动名词（短语）
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：简化为“宾语+V-ing形式（作宾语补足语）”
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：简化seem后的宾语从句
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
七，其他需要说明的问题
1．标点由主句决定，如主句是陈述句、祈使句，则用句号；是疑问句则用问号。
eg. I heard she had been to the Great Wall.
Can you tell me which bus I should take?
2．要注意个别句子中主从句人称的一致。
3.宾语从句和状语从句的区分
eg. 1） I will go out tomorrow if it is fine.
2） I don't know if the train has arrived.
句1）中if引导的是状语从句。这个从句表示“条件”，修饰主句。整个句子的意思是如果明天天气好，我就出去。
句2）中if引导的是宾语从句，充当谓语动词don't know的宾语。整个句子的意思是我不知道火车是否到达。
判断方法：
1．从位置看：
状语从句一般可以放在主句的前面或后面（个别除外），宾语从句只能放在主句谓语动词之后。
2．从引导词看：
if充当宾语从句的连接词时，相当于whether，词义为“是否”，充当状语从句的连接词时，词义为“如果”。when充当宾语从句的连接词时，意为“什么时候”，充当状语从句的连接词时，意为“当……的时候”。
3．从时态看：
if和when作连接词时，引导宾语从句要注意：从句的谓语动词的时态应根据主句的时态作相应的变化。if和when充当从属连词时，引导条件和时间状语从句，若主句的谓语动词用一般将来时，则从句的时态应用一般现在时表示将来（即”主将从现”）。
八。典型错句解析
1. He doesn’t know that when she can return him his book.
【解析】…know that when she →…know when she …引导宾语从句的连词不可同时使用．
2. He doesn’t like that I’ve brought him.
【解析】that→what，what引导宾语从句时，常无疑问意义，表示“所……人(物)”,在从句中作主语,宾语或表语．
3. It’s a question of if we should help her.
【解析】if → whether介词后接的宾语从句不能用if而应用whether 引导．
4. Could you tell me where is she?
【解析】is she→ she is．宾语从句一律用陈述句语序，即谓语动词位于主语后面．
5. I think you are going to the park, don’t you?
【解析】don’t →aren’t you．在I think that…结构中，其后反意疑问句附加部分，要与that之后的从句主，谓一致．
6. Could you tell you me which place she lives?
【解析】lives→lives in. 宾语从名中的动词不是及物动词，后面要带介词．
7. He asked me when the train will arrive.
【解析】will→would.主从时态要前后呼应，主句为过去时，从句要用过去时形式．
8. I don’t know that I said.
【解析】that → what. that引导宾语从句时，其本身无词义．what作said 的宾语．
