虚拟语气的用法

一、虚拟语气用于假设（详见第143节专题“条件和假设”）

二、虚拟语气用于以 as if 和 as though（好像）引导的方式状语从句中，表示不太符合实际的比喻

1. This mini computer operates as if it were a new one. 这台小型计算机操作起来像一台新的一样。（事实上这台小型计算机不是新的。）
2. This micro computer operates as though it had been repaired. 这台微型计算机操作起来好像修理过似的。（事实上这台微型计算机操作前没有进行过修理。）

注：在 look 和其它个别动词后引起的 as if 或 as though 的从句内，可以用虚拟语气，目前有趋势，也可以用陈述语气，因为 as if 和 as though（作“好像”讲）已衬托出虚拟语气的含义。

1. She looks as if she is from Beijing. 她看起来像北京人。
2. It seems as if we shall have to walk home. 看来我们似乎得步行回家了。
3. It sounds as though someone is knocking at the door. 听起来似乎有人在敲门。

三、虚拟语气用于以 lest, for fear that 和 in case 引导的目的状语从句中

1. He is working hard for fear that he should fall behind. 他工作努力，怕落在别人后面。
2. I wrote everything down lest I should forget it. 为了怕忘记，我把每件事都记下来了。
3. Take your umbrella along, in case it should rain. 带着伞吧，以防下雨。

必须注意，上述三个目的状语从句内的 should 还可以省略，于是就以动词原形出现。

四、虚拟语气用于 though (或 although) , even if 和 even though 引出的让步状语从句中，表示已不把让步作为事实，却把它当作假设来用

1. Even though she had been very busy, she would have helped us. 即使当时她很忙，她还是会帮助我们的。（事实上她当时并不十分忙，故更会帮助我们。）
2. Even if he were here, he could not solve the problem at once, either. 即使他在这里，他也不能立即解决这个问题。（事实上他没有在这里。）
3. Though (或 Although) he blame me, yet will I trust in him. 即使他责备我，我还是依然信任他。

上句是用动词原形表示虚拟语气，借以体现不把让步当作事实。与此同理，如果在条件从句内也采用动词原形表示虚拟语气，当然也可把条件转为假设。例如：

If the news be true, his life is in the greatest danger. 如果这消息确实，那么他的生命处于极其危险之中。（注意主句并没用虚拟语气。）

五、虚拟语气用于表示愿望的固定句型结构中

1. You had better clear up this problem. 你最好将这个问题解释清楚.
2. We would like to see her. 我们愿意见她。
3. Lisa would sooner go downtown than stay here. 莉萨宁愿去市中心区而不愿呆在这里。
4. I had (或 would) rather take this than that. 我宁愿取这个而不要那个。
5. He would rather you didn't do that for the time being. 他宁可让你暂时不做那件事。
6. Prof. Lu would as soon get online as go to the cinema. 卢教授宁愿上网而不去看电影。

六、虚拟语气用于主句中含有建议、劝告、要求、请求、需要、愿望、命令等词语的有关从句中，体现一种“让某人做某事”的主观意向

1. They suggested that the World Cup be held every two years. 他们那时建议（让）世界杯每两年举行一次。
2. I recommended that he (should) study more English before going abroad. 我建议（让）他出国前多学点英语。（宾语从句用虚拟语气。）
3. They require that this work (should) be done at once. 他们要求立即做这项工作。（宾语从句用虚拟语气。有“让这项工作立即做”的含义。）
4. She thinks it necessary that we should obtain experience through practice. 她认为有必要让我们通过实践取得经验。（it 为形式宾语，后面从句为真正宾语，并用了虚拟语气。）
5. His idea is that we（should）send a teacher to teach them English. 他的意见是让我们派一名教师去教他们英语。（表语从句用虚拟语气。）
6. I agree to the proposal that we (should) put this question to the vote. 我同意这个提议一一让这问题付诸表决。（同位语从句用虚拟语气。）
7. It is desired that you (should) put yourself in his position. 希望（让）你设身处地为他想一想。（主语从句用虚拟语气。）
8. It will be better that we (should) hold a meeting next week. 最好（让）我们下周开一次会。（主语从句用虚拟语气。）
9. He ordered that the soldiers should put out the lights immediately. 他命令（让）战士们立即熄灯。（宾语从句用虚拟语气。）

注：属于本类用法的词语还有：demand, propose, command, request, insist, suggestion, recommendation, motion（作“动议”讲），plan等。见到这些词，后面从句用 should 或用动词原形，便是虚拟语气的用法了。

七、虚拟语气用于表示祝愿的祈使句中，一般用动词原形或 may 加动词原形

1. Long live the friendship between the peoples all over the world. 全世界人民友谊万岁！
2. May your life be long. 祝（愿）君长寿！

八、虚拟语气用于表示主观揣测和婉转的语气

1. At that time the temperature would rise rapidly. 那时温度会迅速上升。（句中 would 表示主观揣测的意味。若用 will，语气就很肯定。）
2. Would you write a letter to him? 你要不要给他写一封信？（婉转语气。用 will 就不如 would 显得客气。）
3. Might I come in? 我可以进来吗？（用 might 比 may 语气婉转。）

九、虚拟语气用于 it is time 后的定语从句中

1. It is (high) time (that) we (should) set off. 我们该动身了！
2. It is time (that) we got up. 我们该起床了！（本句用一般过去时表示虚拟语气。关系副词 that 常省略。) 在本句型中，第 2 句的虚拟语气表示法比第 1 句用得更广泛.

十、虚拟语气用于表示惊奇、疑惑、没料到的事

1. It is strange that she should have failed to do this test. 奇怪的是，她竟然没有做成这项试验。
2. It is wonderful that she should have completed the experiment in a short time. 她竟然用很短时间做完这个实验，真令人惊异。
3. In ever thought that the problem should be so easy. 我从来没想到这问题居然会如此容易。
4. We just couldn't believe that the new building should be so beautiful. 我们简直不相信新楼会这样漂亮。

注：对过去事实表示惊奇，should 后用完成式动词；对今后的事表示惊奇，则 should 后用一般式动词。

十一、虚拟语气用于 it is important (或 natural)，it has been decided, I am sorry, they were disappointed 等句子后面的从句中

1. It is very important that China should join WTO. （让)中国加入世贸组织是非常重要的。
2. It is natural that I should drop in on my teacher. 自然我要顺便走访我的老师。
3. It has been decided that we should have English classes next week. 已经决定（让）我们下周上英语课。
4. I am sorry that he should be so weak. 很遗憾，他身体（竟然)这样弱。

十二、注意 should, would 和 might 等用于虚拟语气和作其它用法时的区别。详见 should，would 和 might 各自用法的专题介绍（参阅第 65，96，132 有关项)。