一、宾语从句的语序必须是陈述语序。如：?
Do you know why winter is colder than summer?你知道为什么冬季比夏季冷吗?? 

二、宾语从句与主句的时态要相互呼应。?
主句是现在或将来时态时，从句可用任何所需要的时态。主句是过去时态时，从句要用表示过去的相应的时态。但如果从句中有明确表示过去的时间状语，则从句应用一般过去时，不用过去完成时；如从句表达的是客观规律或真理时，用一般现在时。如：?
He said he had finished his studies when the war broke out.他说战争爆发时，他已经完成了学业。
He said he would spend his holiday in Dalian.他说他将在大连度假。?
She said that the earth moves around the sun.她说地球围绕太阳转。? 

三、如宾语从句有自己的宾语补足语，则用it作形式宾语，而把宾语从句后置。其句型为：“主语+谓语+it+补足语+宾语从句”。如：
 We think it important that we should master at least one foreign language.
我们认为掌握至少一门外语是重要的。? 

注意：

(1)连词that引导的名词性从句很少作介词的宾语，只用在except,but和in等少数几个介词后。其它一些介词的宾语从句如由连词that引导，则需用it先行一步，作形式宾语。如：
He is a good student except that he is careless.他是个好学生，只不过有点粗心。?
See to it that children don＇t catch cold.当心孩子别感冒了。?

(2)that引导表语从句时，在句中无词义，只起连接作用，但不可省去。His idea is that we should go there at once.他主张我们立即去那儿。? 

四、连词whether可引导主语从句、宾语从句和表语从句，不可省。if引导宾语从句。 

(1)宾语从句是肯定句时，whether,if可互换；但whether常和or not连用，宾语从句是否定句时，一般用if引导。如：?
I don＇t know if/whether I should tell you.不知我是否应告诉你。?
I wonder whether it is true or not.不知这是不是真的。?
I don＇t care if it doesn＇t rain.天下不下雨我不会在乎。? 

(2)作介词宾语时，只能用whether,不能用if。如：?
Everything depends on whether we have enough experience.一切都取决于我们是否有足够的经验。

五、that引导宾语从句时不可省的几种情况：?
 
1.that宾语从句的状语部分位于从句前部时。?
I promised that if anyone could set me free,I would make him king over the earth.
我曾许诺如果有人把我放了，我就让他成为全世界的国王。? 

2.当主句的状语部分位于that宾语从句前时。?
Abraham Lincoln later said himself that he only went to school a little now and a little then.
亚伯拉罕·林肯自己后来说他只不过是时断时续地接受教育。? 

3.主句的谓语动词与宾语从句之间有插入语时。?
When he got to England,he found,however,that his English was too limited.
然而当他到英国时，他发现他的英语很有限。? 

4.当一个谓语动词带两个或两个以上的that引导的宾语从句时。
 Then he said that French was the most beautiful tongue in the world,and that we must keep it among us and never forget it.
他说，法语是世界上最美的语言，我们必须坚持说法语，永远也不要忘记它。? 

5.宾语从句是双宾语中的直接宾语时。?
I must never tell anyone that I could not see the cloth.
我决不能告诉任何人我看不到那布。? 

6.宾语从句的主语是this/that，或用this/that修饰主语时。?
He said that that was a good idea.他说那是个好主意。? 

7.在直接引语中，主句和宾语从句被隔开时。?
“I＇m sorry to tell you,”he said,“that you didn＇t watch carefully enough what I did.”
我很遗憾的告诉大家，你们没有仔细观察我所做的一切。? 

8.宾语从句的主语是非谓语动词或主语从句时。?
The old lady then explained that what she was looking for was a pair of gloves for a girl.
那位老太太解释说她在为一个女孩找一双手套。