if引导的条件状语从句-虚拟语气.doc

虚拟语气是一项语法难点，为了让学员们便于理解与记忆，我们把虚拟语气分成三大块来讨论：
1．名词从句中的虚拟语气 标志词+should+动词原形
2．条件从句中的虚拟语气 ①三种基本态 ②倒装虚拟句 ③混时虚拟句 ④含蓄虚拟句 ⑤跳层虚拟句
3．其它情形中的虚拟语气（wish/would rather/It’s high time…/If only…/lest）

一．三种基本形态（1）
表虚拟的时间 if从句谓语形式 主句谓语形式
现在： did / were would (should, might, could)+do
过去： had done/ had been would (should/might/could)+have done(been)
将来： were to/ should+do would (should, might, could)+do

三种基本形态（2）（这是基础，建议牢记下面的例句，争取能脱口而出）
与现在事实相反：If I had enough money, I would buy a book.
与过去事实相反：If I had had enough money, I would have bought a book.
与将来事实相反：If I were to have enough money, I would buy a book.
If I should have enough money, I would buy a book.

二、倒装虚拟句（只能与过去/将来事实相反，省去if，只有三种倒装形式）
Had I had enough money, I would have bought a book.
Were I to have enough money, I would buy a book.
Should I have enough money, I would buy a book.

三、混合时间虚拟语气（主要是抓住时间状语）
对过去事实虚拟+对现在事实虚拟)
If I had studied English at school, I could read the English novel now.
(对现在事实虚拟+对过去事实虚拟)
If she were not so careless, she wouldn’t have made such a mistake.

四、含蓄虚拟句（在四级考试中目前还未出现此考点，但在阅读中常见）

3. 虚拟语气用在主语从句中。在句型“It is important (necessary, strange, natural等) that. 中，that 后面的从句中的谓语动词用(should) + 动词原形。

It's necessary that we should have a walk now. 我们现在有必要出去散散步。

What would I have done without you?
But for their help, I would not have finished the task.
But that the doctor arrived on time that day, they would have been dead.
Given more time, I would have been able to finish the test.

五、跳层虚拟句（即句子一半为虚拟，另一半为陈述语气；but前句用虚拟而or/otherwise后句用虚拟） (but)
He would put on weight, but he doesn't eat much. (与现在事实相反)
He would have put on weight, but he didn't eat much. (与过去事实相反)
(or, or else, otherwise)
I forget where I read the article, or I would show it to you now. (与现在事实相反)
Mary couldn't have received my letter, otherwise she would have replied before now. (与过去事实相反)

六、名词从句虚拟语气
(1) ask, advise, beg, command, demand, decide, desire, insist, order, prefer, propose, require, recommend, request, suggest, urge等表示命令、要求、建议等含义的动词后的宾语从句中，谓语动词用(should)+动词原形, eg. I suggest / suggested that we (should) go tomorrow.名词从句虚拟语气
(2) It is +(形容词/过去分词/特定名词)+that的从句中，形容词主要是表示令人吃惊的、重要的、必要的、关键的等词汇。形容词：astonishing, amazing, advisable, appropriate, crucial, desirable, essential, important, imperative, keen, necessary, natural, normal, odd, proper, preferable, strange, sorry, shocked, surprising, urgent, unusual, vital等。名词从句虚拟语气
(3) 过去分词：decided, desired, demanded, ordered, requested, recommended, suggested等;名词：advice, decision, desire, demand, suggestion, motion, pray, resolution, wish, preference, proposal, recommendation, requirement, idea, order等

七、其它虚拟语气
Wish…
I wish I knew the answer.(与现在事实相反)
I wish I had known the answer. (与过去事实相反)
I wish you would shut up. (与将来事实相反)

If only…
If only I were taller. (与现在事实相反)
If only he had followed your advice! (与过去事实相反)
If only the rain would stop. (与将来事实相反)

It is (high/about) time…
It is time you thought about your future.

would rather…
I would rather you didn’t speak rudely to her. (与现在事实相反)
I’d rather you hadn’t spoken rudely to her. (与过去事实相反)

Lest…, in case…, for fear that…（引导的是目的状语从句，但可归入第六点(名词从句虚拟)，这是因它们答案特征相同，即 (should)+动词原形。eg.
He took his umbrella lest it should rain.

大学英语虚拟语气考题总结:答案的特征
1.(should)+动词原形(一般式/被动式/否定式)记住信号词（名词，动词，形容词，分词等）以及lest.
2. 一般过去时：wish/If only…/would rather/It’s time (high/about) that….
3.基本形式（主要考与过去和将来相反的虚拟语气）,特别注意时间状语(混合时间虚拟)
4.倒装的两个时间：与过去，与将来相反；三个形式(Had/Were/Should)提前大写，if省去；
5.but/or/or else/otherwise(跳层虚拟语气)
虚拟语气在四级考试中是一个必考的考点。其中，最常考的是它在宾语从句中的用法。一些表示主观判断、推测、建议、命令和要求的动词通常引起虚拟的宾语从句，此类动词后的宾语从句中采用should ＋do（其中 should可以省略）的虚拟语气形式。该类动词包括：

（1）高中词汇：advise（劝告）、ask（要求）、decide（决定）、insist（坚持）、order（命令）、suggest（建议）等。

（2）四级常考词汇：command（命令）、demand（要求）、desire（渴望）、prefer（宁愿）、propose（提议）、recommend（劝告）、require（要求）等。

（3）其他词汇：consent（同意）、maintain（主张）、move（提议）、urge（极力主张）、vote（提议）等。

例句：I recommend that you be diligent if you want to pass the exam．如果你们想考试及格，我劝你们勤奋学习。

特别提示：在复习时，可以把相似用法归类记忆。当一个动词后面的宾语从句中应使用（should）＋do的虚拟语气形式时，则可推理出用法相同的以下一组从句（以动词advise为例）：

（1）I advise that we stay and wait here．（动词后的宾语从句）

（2）It is advised that we stay here．（It is ＋动词的过去分词＋that引导的主语从句）

（3）It is advisable that we stay here．（It is ＋由该动词派生的形容词＋that引导的主语从句）

（4）My advice is that we stay here．（由该动词转换的名词后面的表语从句）

（5）I offered the advice that we stay here．（由该动词转换的名词后面的同位语从句）

（6）I think it advisable that we stay here．（由该动词转换的形容词作宾语补足语，it为形式宾语，真正的宾语从句中使用虚拟语气）

以上六类从句中谓语动词都使用了should ＋do的虚拟语气形式，其中，should可以省略。

由上类动词派生的常考名词有：advice（忠告）、deciion（决定）、demand（要求）、desire（渴望）、order（命令）、 preference（偏爱）、proposal（建议）、recommendation（劝告）、requirement（要求）、suggestion（建议）等。

相关的形容词或过去分词有：advisable（合理的）、 desired（期望的）、desirable（合乎需要的）、insistent（坚持的）、ordered（命令的）、preferable（更可取的）、proposed（建议的）、required（要求的）、urgent（紧迫的）等。

例句：His proposal is that we turn off TV for half an hour every day．（表语从句）他建议我们每天少看半个小时的电视。

It is highly desirable that a new president be appointed for this college．（主语从句）急需为这所大学任命一位新校长。

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