宾语从句在复合句中做主句的宾语,是初中英语教学大纲规定掌握的二种复合句之一,是非常重要的语法项目 ,学习时应从下面几个方面去系统掌握：
一.连词
1.宾语从句具有陈述意义时用that引导,在口语或非正式文体中常省略.如：He said (that)he had been to Beijing.他说他去过北京.
I'm sure(that)she won't mind.我肯定她不会介意的.
2.宾语从句具有一般疑问意义时用连词if 或whether引导,口语中常用if.如：She asked me if(whether) she could come in.她问我她是否能进来.
He asked if you had white hat.他问你是否戴着白色的帽子.
注意：if和whether在用法上是有区别的.(1)if可以引导条件状语从句,whether不能.如：I 'm coming here if it doesn't rain tomorrow.(如果明天不下雨我就来这里.) (2)在下列情况时只能用whether：用作介词的宾语时；用在不定式前面时；whether引导的从句置于句首时.如：
It depends on whether I have enough time.这得由我是否有足够的时间来决定.
He doesn't know whether to go or not.他不知道要不要去.
Whether this is true or not,I can't say.这是不是真的,我说不准.
(3)whether和if常与or not连用,whether和or not 既可合起来使用,也可分开使用；if和or not只能分开使用.如：
He asked whether(if)they would come or not.他问他们是否该来.
I don't know whether or not they will come.我不知道他们来不来.
(4)whether 引导的宾语从句一般是肯定句,if 引导的宾语从句可以是肯定也可以否定的.如:
She asked whether/if you had enough money.她问你是否有足够的钱.
I don't care if it doesn't rain.我不在乎是否下雨.（只能用if)
3.宾语从句具有特殊疑问含义时用连接代词（what,who,which,whose)或连接副词（when,where,why,how)以及有how构成的词组how many,how long等.如：The children didn't know who Father Christmas was.孩子们不知道圣诞老人是谁.Do you know when they'll leave?你知道他们什么时候离开?
值得注意的是,宾语从句与主句之间需要有连词进行连接,除that可以省略外,其它连接词是不能省略的,更不能重复使用.如：“请告诉我们老师讲得什么.”不可以译为：Please tell us that what the teacher said.
二.语序
宾语从句有时是疑问句的意思但语序必须是陈述句语序.特别是由助动词构成的疑问句做宾语从句时.如：
我想知道他在做什么.[误]I want to know what is he doing.
[正]I want to know what he is doing.
告诉我他什么时候离开的.[误]Tell me when did he leave.
[正]Tell me when he left.
三.时态
宾语从句与主句应在时态上保持一致.如果主句是一般现在时,宾语从句可根据实际情况选择适当的时态；如果主句是过去时,从句必须也是过去时的某种时态（一般过去时,过去进行时,过去完成时,过去将来时等）.但当宾语从句叙述的是一普通真理或客观规律时,则用一般现在时.如：
I know he lives here.我知道他住在这里.
I knew who lived here.我知道谁住过这儿.
He said that the sun rises in the east.他说太阳从东方升起.
四.否定转移
主句为I think/believe/guess等时,其后面宾语从句的否定应转移到主句上,且附加问句要按从句确定.有否定转移时,要将否定移回到从句上再决定附加问句的形式.如：I don't think he'll be back,will he?
I think he can answer the question,can't he?
五.宾语从句的简化
宾语从句在一定条件下可以转换成简单句,一般有下列几种方法：
1.用动词不定式代替宾语从句.如:
She hopes that she will be back soon.→She hopes to be back soon.
He agreed that he would help me with my English.→
He agreed to help me with my English.
2.用“疑问词+不定式”结构代替宾语从句.如：
I don't know what I should do next.→I don't know what to do next.
Please tell me how I can finish the work on time.→
Please tell me how to finish the work on time.
3.用复合宾语,即宾语加宾语补足语代替宾语从句.如：
I saw that he went into the house just now.→
I saw him go into the house just now.
Can't you see that the boy is climbing the tree?→
Can't you see the boy climbing the tree?
I heard she was singing in English.→I heard her singing in English.
Tom's mother found he was a very good pupil.→
Tom's mother found him a very good pupil.
4.用名词或名词短语代替宾语从句.如：
Do you understand what I said?→Do you understand my words?
Could you tell me where the hospital is?→
Could you tell me the way to the hospital?