语法

语法点：非真实条件句：与过去事实相反 (Third Conditional)

第三类条件句用来谈论过去没有发生的事，以及它本来会带来的结果，也就是"如果当初……，就会……"。因为条件和结果都与过去事实相反，所以 if 从句用过去完成时（had + 过去分词），主句用 would / could / might + have + 过去分词。本课说：如果 1834 年议会大厦没有被烧毁，大本钟就永远不会被建造。事实是大厦烧了，钟也建了，作者用第三类条件句把这层因果关系表达出来。

结构

类型	if 从句	主句
肯定	If + 主语 + had + 过去分词	主语 + would have + 过去分词
否定	If + 主语 + had not + 过去分词	主语 + would not have + 过去分词
被动	If + 主语 + had been + 过去分词	主语 + would have been + 过去分词
疑问	If + 主语 + had + 过去分词	Would + 主语 + have + 过去分词?

要点：1) if 从句不能用 would；2) 主句情态动词可换成 could / might 表示可能；3) never 等副词放在 would 和 have 之间：would never have been erected。

课文中的例句

[句 2] If the Houses of Parliament had not been burned down in 1834, the great clock would never have been erected. — 典型第三类条件句，从句和主句都是被动语态
[句 9] A painter who had been working on the tower hung a pot of paint on one of the hands and slowed it down! — 可改写为：If the painter had not hung a pot of paint on the hand, the clock would not have slowed down.
[句 8] Once, however, it failed to give the correct time. — 过去发生的事实，可用第三类条件句谈论相反情况
[句 3] Big Ben takes its name from Sir Benjamin Hall who was responsible for the making of the clock… — 可改写为：If Sir Benjamin Hall had not been responsible for the clock, it would not have been called Big Ben.

补充例句

If the painter had been more careful, the clock would not have gone wrong. — 如果那个油漆工当时更小心一点，钟就不会出错了。
If you had visited London last year, you would have seen Big Ben. — 如果你去年去了伦敦，你就会看到大本钟了。
If the microphones had not been connected to the tower, we could not have heard the clock on the B.B.C. — 如果麦克风没有接到钟楼上，我们就不可能在 B.B.C. 上听到钟声。

易错点

❌ If the Houses of Parliament would not have been burned down… → ✅ If the Houses of Parliament had not been burned down… — if 从句用过去完成时，不能用 would。
❌ …the great clock would never be erected. → ✅ …the great clock would never have been erected. — 与过去事实相反的结果要用 would have + 过去分词。
❌ If the painter didn't hang a pot of paint on the hand, the clock wouldn't have slowed down. → ✅ If the painter hadn't hung a pot of paint on the hand, the clock wouldn't have slowed down. — 从句不能用一般过去时，要用 had + 过去分词。
❌ …would have never been erected. → ✅ …would never have been erected. — never 放在 would 之后、have 之前更自然。

逐句语法分析 · 9 句

1When you visit London, one of the first things you will see is Big Ben, the famous clock which can be heard all over the world on the B.B.C.
当你访问伦敦时，你首先看到的东西之一就是大本钟，这座著名的大钟的钟声可以通过英国广播公司传遍全世界。
一般现在时 + 一般将来时 (Simple Present + Simple Future) · When + 从句, one of the first things (that) you will see + is + 名词 + which 定语从句
- when 从句用现在时表将来
- one of the first things 后省略了关系代词 that
- which can be heard 定语从句中的情态动词被动
时间状语从句用现在时；主句 one of the first things you will see is…，which 从句补充说明大本钟。
2If the Houses of Parliament had not been burned down in 1834, the great clock would never have been erected.
如果国会大厦没有在1834年被烧毁，这座大钟也许永远不会建造。
第三类条件句 (Third Conditional) · If + 主语 + had not been + 过去分词, 主语 + would never have been + 过去分词
- 从句 had not been burned down 过去完成时被动
- 主句 would never have been erected 与过去事实相反
- never 放在 would 之后
与过去事实相反的条件句：大厦实际上被烧了，钟也建了。两部分都是被动。
3Big Ben takes its name from Sir Benjamin Hall who was responsible for the making of the clock when the new Houses of Parliament were being built.
大本钟是以本杰明·霍尔爵士的名字命名的，新国会大厦建造期间，他负责这座大钟的制造。
一般现在时 (Simple Present) · 主语 + takes its name from + 名词 + who 定语从句 + when 从句（过去进行时被动）
- take one's name from 得名于
- be responsible for 负责
- were being built 过去进行时被动
主句一般现在时说明事实，定语从句中的 when 从句用过去进行时被动 were being built。
4It is not only of immense size, but is extremely accurate as well.
它不仅体积巨大，而且极为准确。
一般现在时 (Simple Present) · 主语 + is not only + 介词短语, but + is + 形容词 + as well
- not only… but… as well 不但…而且…
- of immense size 相当于形容词 immense
- extremely accurate 极其准确
not only… but… as well 连接两个并列表语，说明大本钟又大又准。
5Officials from Greenwich Observatory have the clock checked twice a day.
格林尼治天文台的官员每天两次派人检查这座大钟。
一般现在时 (Simple Present) · 主语 + have + 宾语 + 过去分词 + 频率状语
- have sth. done 请人做某事
- checked 是过去分词表示被动
- twice a day 一天两次
have the clock checked 表示让人检查钟，不是自己检查；一般现在时表示习惯。
6On the B.B.C. you can hear the clock when it is actually striking because microphones are connected to the clock tower.
在英国广播公司，你可以听到大钟实际敲响的声音，因为麦克风是与钟楼相连的。
一般现在时 (Simple Present) · On the B.B.C. + 主语 + can hear + 宾语 + when 从句 + because 从句（被动）
- when it is actually striking 现在进行时
- are connected to 一般现在时被动
- because 引导原因状语从句
主句用 can hear；when 从句进行时强调正在敲；because 从句用被动说明原因。
7Big Ben has rarely gone wrong.
大本钟很少出差错。
现在完成时 (Present Perfect) · 主语 + has rarely + 过去分词 + 形容词
- has gone wrong 现在完成时表示从过去到现在
- rarely 放在 has 和 gone 之间
- go wrong 出故障
现在完成时概括大本钟至今的表现：很少出错。
8Once, however, it failed to give the correct time.
然而有一次，它没有报出正确的时间。
一般过去时 (Simple Past) · Once, however, + 主语 + failed to do + 宾语
- once 在此意为"有一次"
- fail to do 未能做
- however 表示转折
一般过去时引出一次具体的例外事件，与上句形成对比。
9A painter who had been working on the tower hung a pot of paint on one of the hands and slowed it down!
一位一直在钟楼上工作的油漆工把一桶油漆挂在了一根指针上，使它走慢了！
一般过去时 (Simple Past) · 主语 + who 定语从句（过去完成进行时）+ hung + 宾语 + on… + and slowed it down
- who had been working 过去完成进行时，强调持续到挂桶之前
- hung 是 hang 的过去式
- slow down 使变慢
定语从句 had been working 说明油漆工一直在塔上工作；主句两个过去时动作并列。

练习 · 44 题

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选择正确的答案
1. If the Houses of Parliament ____ down in 1834, the great clock would never have been erected.
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2. If the Houses of Parliament had not been burned down, the great clock ____.
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3. If the painter ____ a pot of paint on the hand, the clock would not have slowed down.
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4. If the painter had been more careful, the clock ____ the correct time.
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5. If microphones ____ to the clock tower, you could not have heard the clock on the B.B.C.
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6. If Sir Benjamin Hall had not been responsible for the clock, it ____ Big Ben.
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7. Officials from Greenwich Observatory have the clock ____ twice a day.
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8. Big Ben ____ rarely gone wrong.
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9. Big Ben takes its name ____ Sir Benjamin Hall.
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10. It is not only of immense size, ____ is extremely accurate as well.