Ⅰ、主语从句
e.g. That the sea covers about three-fourths of the earths surface is well known.
e.g. Which design is more practical is still a question.
根据英语习惯，有的句子可用it作形式主语，放在句首，而将主语从句放在后面，使句子更为平衡。如上面的句子可改为：
e.g. It is well known that the sea covers about three-fourths of the earths surface.
e.g. It is still a question which design is more practical.
小结:
主语从句一般坐落于主语的地方上, 但有时也会出目前句子的末尾部分. 当句子的主语是从句结构时, 谓语部分应该用单数的形式.
Ⅱ、宾语从句
宾语从句可以作动词或介词的宾语。
e.g. They tell me the math course is difficult.
e.g. I wonder whether the refrigerator is large enough.
e.g. Please let me know when the telephone will be installed1.
e.g. He informed me of what they wanted.
比较:
e.g. Please inform him of the fact that Ive seen her.
注：
1. 宾语从句一般紧跟在动词和介词的后面。
2. 引导宾语从句的连词that在口语和非正式文体中常可省略。
3. whether和if都可以表示是不是的意思，在口语中常可以互换，如上面第2个例句，I wonder后面既可用whether也可以用if引出宾语从句，意思不变。但假如作为介词的宾语，或后面跟有or not，或引出主语从句时，则只用whether而不需要if，如：
e.g. It all depends on whether we can get their cooperation.
e.g. Tell me whether you like the handbag or not.
e.g. Whether they will join us hasnt been made clear.
他们是不是参加大家的活动还不了解。
Ⅲ、表语从句
表语从句与系词一块构成主句的谓语结构。
e.g. My problem is how we can reduce this high temperature.
我的问题是大家如何可以减少如此的高温。
e.g. Our conclusion is that, in view of 因为the drought2, there is only enough water for two days.
for： 就而言
e.g. It is rather cold for January.
e.g. She is clever for her age
e.g. It seems that it is going to rain. 表语从句
It seems that 仿佛，好像
It seems to me that 我想，我以为
e.g. The cloth feels as if it were made of silk. 表语从句
Ⅳ、同位语从句
同位语从句用以说明名词的内容，使之明确而具体化。跟有同位语从句的名词一般是一些需要进一步说明其具体内容与含义的名词。如conclusion, doubt, fact, fear, hope, idea, news, opinion, suggestion等。从句一般由that引导，有时也可由whether, what, when, where, why, how等引出。
e.g.There is no doubt that he will succeed.
毫无疑问，他肯定成功。
e.g.My opinion that no action need be taken yet is shared by most of us here.
我的建议是目前还无需采取行动，这是大家这里大部分人的共识。
They havent have any idea when it is proper to take action. 对于什么时间合适采取行动, 他们还没任何想法. /他们还没想出什么时间合适采取行动
提示:
在翻译的过程中对同位语从句常常可以采取的处置方法是: 添词+ 结构转换; 或者使用词性转换法+ 结构转换法
下面大家看看实质考试试题中的句子：
Effects of Environmental Pollution
Two spectres haunting3 conservationists have been the prospect)that environmental pollution might lead to the planets4' becoming unbearably5 hot or cold. One of these ghosts has now been laid, because it seems that even an increase in the amount of carbon dioxide in the atmosphere to eight times its present value will produce an increase in temperature of only 2C, which would take place over several thousand years.
