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Unit 5 Working the LandSection Ⅱ Learning About Language
主语从句
考点一 主语从句的定义和连接词
1．定义：在复合句中充当主语的句子叫主语从句。
How he was successful is still a puzzle.
他是如何成功的仍然是个谜。
2．连接词的选用
(1)that 和 what 的选用：that 和 what 都可引导主语从句。what 除了起连接作用外，还在名词性从句中充当某些成分，如主语、宾语或表语。而 that 在名词性从句中不充当任何成分，无词义，只起连接作用。
What he wants is a storybook.
他想要的是一本故事书。
That light travels in straight lines is known to all.
众所周知，光沿直线运动。
(2)if 和 whether 的选用：whether 和 if 尽管不充当句子成分，但含有“是否”的意思。whether 和 if 也有不同的用法：if 可以引导主语从句，但从句不能用于句首，而应该放在句尾，并用 it 作形式主语。whether还可以与or not连用，语意不变。
Whether we will hold a party in the open air tomorrow depends on the weather.
我们明天是否在户外开晚会要视天气而定。
(3)其他连接词的选用：根据主语从句的具体意义，还可选择 who, which, when, where, why, how 等连接词，这些连接词既有疑问含义，又起连接作用，同时在从句中充当成分。
When we shall hold our sports meet is not decided.
我们何时举行运动会还没有决定下来。
Who broke the glass yesterday is not clear.
昨天是谁打破的玻璃还不清楚。
Which car you will choose to buy makes no difference.
你选择买哪辆车不会有任何区别。
(4)whatever 和 whoever 的选用：whatever 和 whoever 在主语从句中不含疑问意义，不仅起连接作用，还在从句中作成分。whatever 相当于 anything that; whoever 相当于 anyone who。要注意 whatever, whoever 引导的主语从句和让步状语从句的区别。试比较：
无论谁破坏法律，都应受到惩罚。
Whoever breaks the law should be punished.(＝Anyone who breaks the law should be punished.) (whoever 引导的是主语从句)
Whoever breaks the law, he should be punished.(＝No matter who breaks the law, he should be punished.) (whoever 引导的是让步状语从句)
考点二 由 it 作形式主语的主语从句
1．由 that 引导的主语从句，在大多数情况下会放到句子的后面，而用 it 作形式主语。
It is wellknown that the earth moves around the sun.
众所周知，地球围绕太阳转。
提示：
需要注意的是，it 作形式主语代替主语从句时，要注意和 as 引导的定语从句的区别。试比较：
据报道，美国遭到恐怖分子的袭击。
It was reported that the US was under the terrorist attack.(it 代替主语从句，句中有 that，无逗号)
As was reported, the US was under the terrorist attack.(as 引导定语从句，句中无 that，有逗号)
2．用 it 作形式主语的常见句型
(1)It＋be＋形容词＋that 从句
这类形容词有 necessary, essential, clear, true, strange, important, possible, likely等。需要注意的是，当形容词是 necessary, strange, important, essential 等时，主语从句的谓语用“(should＋)动词原形”，即从句要用虚拟语气。
It is necessary that you (should) master the computer.
你有必要精通电脑。
It is important that a student learn English well.
学生学好英语很重要。
It's clear that they badly need help.
很明显，他们急需援助。
(2)It＋be＋名词(词组)＋that 从句
这类名词(词组)有 a fact, a good idea, a pity, a shame, no wonder等。
It's a pity that you missed the film.
你没有看那部电影真是太遗憾了。
It's no wonder that you're so tired.
难怪你这么累。
(3)It＋be＋过去分词＋that 从句
这类过去分词有 reported, wellknown, hoped, thought, expected, said, believed, suggested, ordered等。当过去分词是 suggested, advised, ordered, requested, insisted, required 等时，主语从句的谓语用“(should＋)动词原形”，即从句要用虚拟语气。
It is suggested that the meeting be put off.
有人建议会议延期召开。
It's said that Mr Green has arrived in London.
据说格林先生已到达伦敦。
(4)It＋不及物动词(短语)＋that 从句
这类不及物动词(短语)有 seem, happen, occur, matter, make a/no difference等。
It seems that they will win the game.
看起来他们好像会赢得这场比赛。
It happened that I had no money with me that day.
碰巧那天我身上没带钱。
考点三 主语从句需注意的问题
1．that 引导的主语从句置于句首时，that 不能省略；如果用 it 作形式主语，主语从句的引导词 that 通常也不可省略。
That he was ill yesterday is known now.
大家都知道他昨天生病了。
That you don't like him is none of my business.
你不喜欢他不关我的事。
2．if 引导主语从句时只能用 it 作形式主语，而把主语从句放在句末。
It is uncertain if he will leave for Beijing tomorrow.
明天他是否去北京还不敢肯定。
3．从句的语序：在任何情况下，主语从句都用陈述语序。
Who did this is still unknown.
这件事是谁做的还不知道。
What surprised me most was that the little girl could play the violin so well.
使我感到惊讶的是，这个小女孩的小提琴拉得太好了。
4．单个的主语从句作主语时，谓语动词一般用单数形式。但 what 和 who 引导主语从句时，谓语动词的形式应与作表语的名词保持一致。
What we need are more personal computers.
我们需要的是更多的个人电脑。
What we need is more time.
我们需要的是更多的时间。
单句语法填空
1．What struck me most in the movie was the father's deep love for his son.
2．What you said at the meeting describes a bright future for the company.
3．What makes the book so extraordinary is the creative imagination of the writer.
4．It is by no means clear what the president can do to end the strike.
5．It doesn't matter whether you pay by cash or credit card in this store.
6．It suddenly occurred to him that he had left his keys in the office.
7．The limits of a person's intelligence, generally speaking, are fixed at birth, but whether he reaches these limits will depend on his environment.
8．Everyone in the village is very friendly.It doesn't matter whether you have lived there for a short or a long time.
9．How medicine works in a human body is a question that not everyone can understand fully.
10．Why the dinosaurs disappeared still remains a mystery.
11．His father got him a job in a bank but soon it became clear that he was not fit for that kind of work.
12．Grandma pointed to the hospital and said, “That's where I was born.”
13．Whether we'll go camping tomorrow depends on the weather.
14．When the delayed flight will take off depends much on the weather.
15．That he lost his balance made him slip on the ice.
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