seaGrammar主语从句.ppt

名词性从句在一个句子中充当主语的时 候，我们称之为主语从句。 That food companies (should) often use red, green, orange and yellow is not surprising. 主语从句可以由 that引导。引导词 that在主语从句中不作任何成分, 也没有中文意义。当主语从句位于句首时, that不能省略。 That we need more practice is quite clear. That they come to our rescue deeply touched our hearts. That her hair was turning grey worried her a bit. 2. 如果主语很长,常用以 “it”作形式主语的结构。 It is a fact that English has been accepted as an international language. 英语已成为一种国际性的语言是不争的事实。 =That English has been accepted as an international language is a fact. 常见的it作形式主语的结构: It + be +adj.+ that 从句 It + be + said/believed/known +that从句 It + seems/happens/appears +that 从句 It+ be + a pity/fact +that从句 It is important that we should learn a foreign language. It is still unknown which team will win the match. It seems that everyone knows what has happened. It is a pity that you failed to pass the exam. 3. 主语从句也可以由疑问代词(what, who, whom, which哪一个)和疑问副词(where, when, why, how)，或wh-ever类疑问词引导。 What colours meant to early humans is little known to us. Who she will invite to her birthday party is not my concern. Where the next World Expo will take place is known to almost everyone. Where the next World Expo will take place is known to almost everyone. When the meeting will be held has not been decided yet. Why he gave up singing is of great interest to reporters. How the little boy got out of the cave remains a secret. 4. 主语从句作主语往往被看作单数。 When and why Jack came to Shanghai is not known. 不知道杰克是什么时候和为什么来上海的。 5. 由疑问词引导的主语从句要保持陈述语气。 What we should do before the meeting is not clear. 6. 由疑问词引导的主语从句，同样可以用 “it”作形式主语。 It is pretty well understood what controls the flow of carbon dioxide in and out of the atmosphere. 是什么控制着二氧化碳在空气中的含量在今天是很好理解的。 7.主语从句也可以由whether引导，用以描述两种截然不同的可能性。 注意: 1). if 也表示是否，可以引导宾语从句,但是主语从句，表语从句只能用whether引导。 2)or not 通常可以直接跟在whether后面，或者在主语从句中的宾语或宾语补足语后面，或者省略。 Whether we can solve this problem remains unknown. Whether this material can be used in our factory has not been decided yet. Whether p