以下是小編整理的主語從句的講解，希望對大家有所幫助
[尋規找矩]
請觀察下列句子，注意劃線部分句子的意義及用法。
1. What surprised me most was that the little girl could play the violin so well.
2. Who will go to the concert is not known.
3. That she was chosen made us very happy.
4. Whether she will come or not is still a question.
5. Which book they will choose is still unknown.
6. When we shall hold our sports meet is not decided.
7. It’s strange that he knows nothing about it.
8. It is a pity that she has made such a mistake.
9. It is said that President Jingo will visit our school next week.
[小結歸納]
(一)語序
主語從句使用陳述語序，其通常結構爲“引導詞 + 主語 + 謂語 + 其他成分”;但當連接代詞同時充當從句主語時，其結構爲“連接代詞 + 謂語 + 其他成分”，如句1、2。
(二)引導詞
① that引導主語從句時無詞義，也不充當任何成分，但通常不可以省略，如句3;
② whether引導主語從句時意爲“是否”，通常不能用if來代替,如句4;
③ 可以引導主語從句的連接代詞主要有：who, whom, whose, what, which, whatever, whoever等，如句5;
④ 可以引導主語從句的連接副詞主要有：where, when, how, why等，如句6。
(三)常見句型
有時爲避免句子頭重腳輕，常用it作形式主語，代替主語從句放在句首，而把主語從句置於句末。常用句型如下：
① It + be + 形容詞 + that 從句， 如句7;
② It + be + 名詞 + that 從句， 如句8;
③ It + be + 動詞的過去分詞 + that 從句， 如句9。
主語從句學習指導
[尋規找矩] 請觀察下列句子，注意主語從句的用法。
1. That the earth travels round the sun is a well-known fact.
2. It is uncertain whether the artist can do it or not.
3. Who will act the lead in the play has not been decided yet.
4. Where the young man has gone is not known.
5. It is not yet decided when and where the test will be given.
[歸納總結]
1. 引導主語從句的詞有連詞that, whether;連接代詞who, whose, whom, whoever, what, which等;連接副詞where, when, whenever, wherever, how, why等。
2. 有時用it作形式主語，將主語從句後置。
[常見錯誤展示] 下列各句均有一處錯誤，請改正並分析錯誤的原因。
1. Light travels faster than sound is common knowledge.
2. If she’s coming or not doesn’t matter much.
3. That the professor said is of great importance.
4. Where will the trees be planted has not been decided.
5. No matter who breaks the rule will be punished.
6. When and where the meeting will be held still remain a question.
7. What were your problems a year ago has now become mine.
8. It was requested that everyone made a speech at the meeting.
[解析與拓展]
1. 在句首加That(並將Light改爲light)。that雖無詞義但引導主語從句位於句首時不能省略。
2. 將If改爲Whether。if, whether都可表示“是否”，但if不能引導位於主句之前的.主語從句，它可以引導位於主句之後帶有形式主語it的主語從句。
3. 將That改爲What。that引導主語從句時無詞義。What the professor said表示“教授所說的”。
4. 將will置於trees之後。主語從句要用陳述句語序。
5. 將No matter who改爲Whoever。引導讓步狀語從句時二者可互換，但引導名詞性從句時只能用whoever。
6. 將remain改爲remains。主語從句表示單一概念時，謂語要用單數形式。
7. has要改爲have。主語從句表示複數概念時，謂語要用複數形式。
8. 將made改爲(should) make。在“It is requested / ordered / suggested + that從句”中，從句要用虛擬語氣，即謂語用“should + 動詞原形”，should可省略。
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