14. 1 概说
语气（Mood）是一种动词形式，用来表示说话者的意图或态度。英语中有三种语气：
1) 述语气（the Indicative Mood） ――用来陈述事实
2) 祈使语气（the Imperative Mood） ――用来提出请求、命令等
3) 虚拟语气（the Subjunctive Mood）――用来表示主观愿望和假想虚拟的情况。
14. 2 虚拟语气
虚拟语气（Subjunctive Mood）是一种特殊的动词形式，用来表示说话人所说的话不是一个实事，而只是一种愿望、假设、怀疑、建议、猜测、可能或纯粹的空想等。凡由If 引起的表示与所述事实相反或根本就不能实现的假设句子，称为虚拟条件句。虚拟条件句根据时间概念可分为以下三种句型：
14. 2. 1 If 从句（动词的过去式），主句（would + 动词原形）。
该句型是表示与现在事实相反的虚拟条件句。从句谓语动词虽然用的是动词的过去式，但与过去无关，表示的是现在或一般情况。如谓语动词是be，一般用were。在非正式场合，尤其是在口语中，主语如果是第一、三人称单数，也可用was代替were。主句谓语除了用would外，还可用should, could或might + 动词原形。例如：
If I had time, I would help you. 如果我有时间我会帮你的。
If I were/was you, I would not be discouraged at all. 如果我是你，我一点都不会泄气。
He might come to school if he were/was not ill. 要是他没病，他可能会到校。
What would you say if she asked you? 如果她问你，你会怎么说？
14. 2. 2 If从句（had+过去分词），主句（would have+过去分词）。
该句型是表示与过去事实相反的虚拟条件句。虽然从句谓语动词用 “had +过去分词”这种过去完成时的谓语形式，但它仅表示过去，而并无“过去完成时”的时间概念。主句谓语用“would/should have + 过去分词”。例如：
If you had come earlier, you would have met her. 要是你早点来，你就会碰见他了。
If I had been here yesterday, he would have done it. 如我昨天在这儿，他就会做了那件事。
You would not have made such great progress if you hadn't studied so hard. 你如果学习不那么努力话，就不会取得这么大的进步。
动词的过去式
14. 2. 3 If 从句 should + 动词原形） ，主句（would + 动词原形）。
were to + 动词原形）
该句型是表示与将来事实相反的虚拟条件句。其主句谓语动词形式与句型I完全相同，只是从句谓语形式稍有不同。从句谓语除了用动词的“过去式”外，还可以用“should或were to + 动词原形”。例如：
If he shouldn't come next week, we would go there. 如果下周他不来，我们就到那儿去。
If I saw him tomorrow, I would give the note to him. 要是我明天见到他，我就把条子给他。
If it were to rain tomorrow, they would stay at home. 如果明天下雨，他们就呆在家里。
If I were free tomorrow, I would go and see my friend. 如果我明天有空，我就会去看望我的朋友。
以上三种句型, 从句和主句中的谓语动词形式都比较固定, 只要根据所述时间便可直接套用。
14. 2. 4 含蓄条件句
有一种假设的情况不是用if条件句来表示，而是用介词短语、分词短语、动词不定式短语、独立结构或连接词等表示，或是通过上下文和句子内在的逻辑关系来暗示。这种句子称为含蓄条件句。他们实际上起着与虚拟条件句相同的作用，因而可以改为相应的虚拟条件句。例如：
Without air and water,there would be no living things.= If there were no air and water, there would be no living things. 没有空气和水，就没有生物。
But for your help, we should not have finished in time. = If you hadn't helped us , we should not have finished in time. 要不是你帮助，我没不会及时完工。
Given more time, we would have done it better. = If we had been given more time, we would have done it better. 如果多给些时间，我们就会做得更好了。
You would be wrong not to help him. = You would be wrong if you did not help him. 如果你不帮助他，你就错了。
Weather permitting, we were to go on a picnic. = If the weather permitted, we were to go on a picnic.如果天气允许，我们就去郊游。
I would have given you more help, but I was so busy. = I would have given you more help if I had not been so busy. 要不是这么忙，我会帮助你的。
I did not receive the invitation, or I would have gone with you. = If I had received the invitation, I would have gone with you. 我没收到请帖，否则我就和你去了。
He worked very hard. Otherwise he would have failed. = If he had not worked hard, he would have failed. 他工作非常努力，要不然他就失败了。
But that I saw it with my own eyes, I could not have believed it. = If I had not seen it with my own eyes, I could not have believed it. 要不是我亲眼所见，我是不会相信的。
〔注1〕 有时可能会出现从句谓语表示的动作与主句谓语所表示的动作在时间上不一致的情况，这时，谓语动词的形式要根据所表达的时间进行调整。例如：
If I had met him yesterday, I would know what to do now. 我昨天要是遇见他, 现在就知道该怎么办了。（从句表示过去，主句表示现在）
I would have gone to the cinema if I were you. 如果我是你, 我就去看电影了。（从句表示现在，主句表示过去）
〔注2〕当 if 引起的虚拟条件句中含有were, had, should或could时，可省略if，这时，从句中的主、谓语则要使用倒装语序。例如：
Were he to leave today, he would get there by Sunday. = If he were to leave today, he would get there by Sunday. 如果他今天动身，星期天他就会到那儿。
Had you come earlier, you would have met him. = If you had come earlier, you would have met him. 你要是早点来，你就碰到他了。
Should it rain, the crops would be saved. = If it should rain, the crops would be saved.如果下雨，庄稼就得救了。
14. 3 非虚拟条件句中的虚拟语气
除了上面介绍的由if引起的虚拟条件句外, 在表示愿望、要求、建议、命令或主张等非虚拟条件句中，有时也需要用虚拟语气，但其谓语动词形式较为特殊。有些动词的形式虽然与陈述语气的某些形式相同，但其用法及所表示的时间概念完全不同。
14. 3. 1 wish 后宾语从句中的虚拟语气
wish 是一个很常用的动词。其后由 that 引起的宾语从句所表示的是不可能实现的愿望，that 常省略。翻译时也较灵活, 可译为“希望、但愿、要是...就好了”等。谓语动词形式有以下三种：
动词的过去式
... wish (ed) (that) 从句… had + 过去分词
would
could + 动词原形
might
从句谓语用“动词的过去式”表示现在不可能实现的愿望，与现在事实相反；用“had + 过去分词”表示与过去事实相反；用“would/could/might + 动词原形”则表示将来难以实现的愿望。从句谓语不可用陈述语气的谓语形式，也不能用“should + 动词原形”谓语形式。例如：
I wish I were/was a doctor. 我要是医生就好了。
I wish I knew what to do. 但愿我知道该做些什么。
How I wish it wasn't raining. 现在要是没下雨该多好。
I wish I had known the answer. 要是早知道答案就好了。
He wished he hadn't done it. 他悔不该当时那么做。
He wishes I would help him. 他希望我会帮助他。
I wish he could try again. 我希望他会再试一试。
〔注〕以上wish均不能用hope替换。虽然两者都可译为“希望”，但 wish表示的“希望”是不可能实现的愿望或实现的可能性极小；而hope所表示的“希望”则是可实现的。因此用hope则需要用陈述语气。比较下面句子：
I wish you hadn't hurt yourself. 但愿你没受伤就好了。（实际上受了伤）
I hope you haven't hurt yourself. 我希望你没受伤。（指没受伤）
I wish I could fly to the moon in a spaceship one day. 希望总有一天我能乘坐宇宙飞船上月球。（实现的可能性极小）
They hope that they can visit China some day. 他们希望有一天能访问中国。（完全有可能实现）
14. 3. 2 名词性从句中的虚拟语气：“should + 动词原形”形式
在有些名词性从句中，需要用“should + 动词原形”来构成虚拟语气的谓语形式，should用于任何人称。口语中常省略should 而直接用动词原形。这种形式常用于：
1)．宾语从句
在表达“请求，要求”（desire,demand, require, request, urge, beg, ask）；“建议，提议”（suggest, propose, advise, recommend）；“命令，嘱咐”（order, command）；“坚持”（insist）等动词后的宾语从句中。例如：
I advise that you (should) go at once. 我建议你该马上去。
He ordered that the door and the windows be shut. 他命令把门窗关好。
He insisted that she come early. 他坚持要她早点来。
He required that we finish the work as soon as possible. 他要求我们尽快完成这项工作。
He demands that one of you go and see him at once. 他要求你们立即去个人看他。
He suggested that we come another day. 他建议我们改天来。
〔注〕当insist作“坚持要，一定要”解时，宾语从句用虚拟语气，表示说话人的主观愿望，所述情况未成事实；作“坚持说，坚持认为”解时，则表示说话人的主观看法，指的是客观事实，用陈述语气。suggest作“建议”解时，其宾语从句用虚拟语气，表示建议做的事还没做；作“表明，说明”解时，则指的是客观事实，用陈述语气。比较下列句子：
He insisted that I (should) have a rest. 他坚持要我休息一下。
He insisted that he didn't need any help. 他坚持说他不需要任何帮助。
The lady insisted that the man had stolen her purse. 那位女士坚持认为那个人偷了她的钱包。
He suggested that we have a meeting tomorrow. 他建议我们明天开个会。
His pale face suggests that he is in bad health. 他那苍白的脸色表明他身体欠佳。
Her attitude suggested that she isn’t really interested. 她的态度表明她不是真的感兴趣。
2)．主语从句
用于“It is + 形容词或过去分词 + that”引起的主语从句中。例如：
It was suggested that we (should) go on a picnic today. 有人建议我们今天去郊游。
It has been decided that you (should) do the job. 已经决定了由你做这项工作。
It was arranged that Miss Lee teach you English. 安排李小姐教你们英语。
It is necessary that he be sent there at once. 有必要马上派他去那儿。
It is very important that everyone master a foreign language. 人人掌握一门外语是非常重要的。
能用于该结构的形容词和过去分词有:important, necessary, natural, strange, imperative；ordered,decided, suggested, arranged, proposed, requested, desired等。
3)．表语从句和同位语从句
在suggestion, proposal, order, plan, request, requirement, insistence, command, necessity, importance, idea, motion, recommendation, understanding, resolution等名词后的表语从句和同位语从句中。例如：
The order was that you stay where you were. 那个命令是要你们呆在原地。
My suggestion was that we plant some trees there. 我的建议是在那儿种些树。
I agree to your idea that the girl be sent there. 我同意你的意见派那个女孩去那儿。
We are for your suggestion that some trees be planted there. 我们都赞同你的意见，在那儿种些树。
14. 3. 3 其他从句中的虚拟语气谓语形式
1)． 由as if, as though引起的状语从句或表语从句中常用动词的过去式或had + 过去分词。例如：
He looks as if he were/was ill. 他看起来好像病了。
He acted as if he were a child. 他的行为就象孩子似的。
He spoke as if he had been there before. 他说话的口气就象他以前去过那儿。
How wild his hair looked, as if it had been electrified.他的头发看起来好乱，象带了电似的。
2)．在由even if, even though引起的状语从句中，动词形式与虚拟条件句相同，根据所述时间来确定。例如：
Even if I knew it, I wouldn't tell you. 即使我知道，我也不会告诉你。
We wouldn't lose heart even if we should fail again. 即使又失败了我们也不会灰心丧气。
Even though I had known his address, I might not have had time to write to him. 即使我早知道了他的地址，我也可能没时间给他写信。
3)．在由so that, in order that引起的目的状语从句中，常用 could / can / might / may + 动词原形。例如：
I lent him my bike in order that he could save some time. 为了节省些时间，我把我的自行车借给了他。
Speak clearly so that they may understand you. 说话清楚些，以便他们能懂得你的话。
4)．在would/had rather后接that引起的从句中，常用动词的过去式或 had +过去分词，that 常省略。例如：
I would rather you went tomorrow. 我宁愿要你明天去。
I would rather they had gone there too. 我宁愿他们也到那里去了。
I would rather they came tomorrow than today. 我宁愿他们明天来而不是今天来。
I would/had rather you posted the letter right now. 我倒希望你把这封信立即寄出去。
5)．在 It is (high) time (that) 后的定语从句中，习惯用动词的过去式，但有时也可用should + 动词原形，that常可省略。例如：
It is time (that) we started. 是动身的时候了。
It is high time I were/was going. 我该走得了。
It is time we stopped / should stop this practice. 现在是结束这种作法的时候了。
It is high time that we (should) put an end to this controversy. 的确该停止这个争论了。
6). 由if only引起的感叹句（谓语形式与wish后宾语从句的谓语相同）。例如：
If only I had known it! 我要是知道这件事就好了。
If only she would come! 要是她能来该多好啊！
Oh，if he only knew how we miss him! 但愿他知道我们多么想他！
〔注〕if only 后接虚拟语气时，作“要是…就好了”，表示强烈的愿望；后接陈述语气，作“只要…就…”解。例如：
I’m sure that he will succeed if only he tries hard. 我相信他只要努力就一定会成功。
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