高中英语语法专项讲义：名词性从句

名词性从句 主语从句 一 由连词引导的主语从句 1． 主语从句可以用that引导，that只起连接作用，在从句中不作任何成分，本身无词义。 That there will be a storm is quite possible，since the wind has changed. 2． 主语从句可以用连词whether（if）引导，它们只起连接作用，在从句中不作任何成分，解作“是否”。whether与if可以互换使用，但是whether可以与or连用，而if却不能与or连用。 If they will be able to come is still a question. Whether he goes or stays is of no consequence to me. 二 由连接代词引导的主语从句 1． 主语从句表示人时可以用连接代词who，whoever引导。 Who did the work is unknown. Whoever does not agree can reserve his view. 2． 主语从句表示物时可以用连接代词what，whatever引导。 What we said is of great importance. Whatever we do should be in keeping with the interests of the people. 3． 主语从句可以用连接代词which，whichever引导。 Which plan is better is clear now. Whichever of you comes in first will receive a prize. 三 由连接副词引导的主语从句 1． 主语从句表示时间时可以用连接副词when引导。 When the meeting will take place has not been decided yet. 2． 主语从句表示地点时可以用连接副词where引导。 Where we shall go to spend our summer holidays will be discussed at the next meeting. 3． 主语从句表示方式或者数量多少时可以用连接副词how，how much（many）引导。 How the telephone was invented is a long story. How many people were present at the meeting is unknown to us. How much water can stay in the air depends upon the temperature of the air. 4． 主语从句表示原因时可以用连接副词why引导。 Why he was late for class is unknown. 四 含有先行词it的主语从句 1． 含主语从句的复合句中，如果主句的表语为名词a fact，a question，a good thing，good news或形容词necessary，important，certain，clear，possible，true，obvious，natural，well-known，strange，ridiculous，funny，remarkable，则主语从句可以置于句首（为了强调或者为了使句子平衡），也可以将形式主语it置于句首而将实际主语（即主语从句）置于句尾。这两种结构中，带形式主语it的结构更为常见，尤其是在口语中。 It is a well-known fact that all matter is made up of atoms. It is still a question whether this material can be used in our factory. It is a good thing that you have come to join us in the discussion. It is good news that our team has won the championship. It is certain that they will help us. It is remarkable that a tablespoonful of soil can tell us so much about the structure and early history of the moon. 2． 含主语从句的复合句中，如果主句的谓语是由某些动词的被动式构成的，则必须用形式主语it置于句首，将实际主语（即