第三节 虚拟语气
一、基本概念
虚拟语气用来表示说话人的主观愿望或假想，所说的是一个条件，不一定是事实，或与事实相反。虚拟语气在条件句中应用比较多。条件句可分为两类：一类为真实条件句，一类为非真实条件句。非真实条件句表示的是假设的或实际可能性不大的情况，故采用虚拟语气。
二、各类从句的虚拟语气
（一）条件从句的虚拟语气
1．构成形式
例1:If I were you, I should/would not watch TV．如果我是你，我就不看电视了。
例2:If I did/had done my homework, I would go/have gone to the party.
如果我做完家庭作业，就去参加晚会。
例3:If you hadn't gone to the cinema, you would not have been late for class.
如果你不看电影，就不会迟到了。
例4:If you had studied harder, you would have passed the exam.
2．应用虚拟的情况
如果你努力学习的话，考试就会及格了。
（1）条件从句中if省略时，要倒装。
如果条件从句的谓语动词包含有were或助动词、情态动词had, should, could，有时可将连词if省去，而将条件从句的主语置于were, had, should, could之后。这种用法主要用于书面语。
1）与现在相反：If I were you（＝Were I you）, I would go with him.
2）与过去相反：If I had had time then（＝Had I had time then）, I would have gone with you.
3）与将来相反：If I were to visit/should visit/visited the Great Wall tomorrow（＝Were I to/Should I visit the Great Wall tomorrow）, I would take my son with me.
（2）without可以代替条件从句。
例：We would not live without water or air．没有水和空气，我们就不能生存。
（3）混合虚拟条件句。
如果条件从句的动作和主句的动作不是同时发生，主句和从句的谓语动词的形式应分别根据各自所表示的时间加以调整。这种句子叫作混合虚拟条件句。
例：If China had not been liberated, the working people would still be leading a miserable life.（从句表示与过去的事实相反，主句说明与现在的事实相反）
中国如果没有解放，那么劳动人民还将处于水深火热的生活中。
（4）用but或but for引导含蓄条件句。（but后跟从句，but for后跟短语：假如没有，要不是）
例1:But for your help, our experiment wouldn't have been so successfu.l
假如没有你们的帮助，我们的实验是不会如此成功的。
例2:We would have invited them to the dance, but they were too busy.
要不是他们太忙，我们会邀请他们来参加舞会的。
（5）“If only...”是一种特殊句式结构。
1）“If only...”用于感叹句中，是一个保留条件句，省略了主句的形式，用来表示某人对某事的一种强烈愿望或未实现的条件，其意为“但愿……，真希望……，要是……就好了”。
例：If only you had worked with greater care！你当时干活时要是再认真些就好了！
2）If only后常用过去将来时表示将来不大可能实现的愿望。
例：If only she would win！但愿她能赢！
（二）宾语从句的虚拟语气
表示请求、命令、建议的动词一坚持（insist），二命令（order, command），三建议（suggest, propose, advise），四要求（demand, require, request, command）以及determine, decide, intend, move, prefer, recommend, urge, desire, direct等谓语动词用（should）+do。特殊情况：suggest作为“表明，暗示”时，不用虚拟语气。insist作为“坚持认为”时，不用虚拟语气。
（三）主语从句的虚拟语气
基本句型：
It is important/necessary/strange +that+主+（should）do.
例：It is necessary that we（should）master a foreign language to find a good job.
掌握一门外语对找到一份好工作来讲很重要。
此类形容词有：
appropriate, advisable, better, desirable, essential, imperative, important, insist-ent, natural, necessary, preferable, strange, urgent, vital等。
相关过去分词有：
desired, demanded, ordered, requested, suggested, recommended, required等。
（四）状语从句的虚拟语气
1．方式从句
例：She felt upset and sad as if/as though the whole world had turned against her.
她很悲伤，仿佛整个世界都背叛了她。
2．让步从句
例：Even if/Even though he apologized to me, I wouldn't pardon him.
即使他向我道歉，我也不会原谅他。
3. It is（high, about）time+从句
从句应该用虚拟语气，值得注意的是用过去时态表示虚拟。或should + 动词原形，should不能省。常译为“是（正是）……的时候”。构成方式为：
It is（high, about）time +that +clause（were/动词用过去式或should+V）
例：It is time（that）we went/should go home．我们该回家了。
（五）表语从句、同位语从句中的虚拟语气
像suggestion, plan, order, advice, resolution, pray, decision, motion, preference, proposal, recommendation, desire, demand, requirement, necessity, request, idea等名词后面的表语从句、同位语从句中要用虚拟语气，即should+动词原形，should可省略。
例1:My idea is that we（should）get more people to attend the conference.
我的想法是让更多的人来参加会议。
例2:I make a proposal that we（should）hold a meeting next week.
我建议下周我们开个会。