时间：2022-07-17 05:37:18
虚拟语气表示说话人的愿望、假设、猜测或建议，不是表示客观存在的事实，因此虚拟语气常用在含有非真实条件从句的主从复合句中。 虚拟语气在条件句中的用法：
虚拟条件句是用谓语动词的特殊形式来表示与现在、过去事实或将来事实相反的情况。虚拟条件句中所用的谓语动词的过去时、过去完成时、过去将来时等只表示不同的虚拟语气，与陈述语气句中的过去时、过去完成时等没有关系。具体情况如下：
1. 表示与现在事实相反的假设时，条件从句中的谓语动词用“过去式(be的过去式用were)”，而主句中的谓语动词用“would (should, could, might) + 动词原形”。例如：
If he had time, he would attend the meeting.
如果他有时间，他会参加这次会议。
If I were a bird, I could fly in the air.
如果我是一只小鸟，我就能在空中飞行。
2. 表示与过去的事实相反的假设时，条件从句的谓语动词用“had + 过去分词”，主句中的谓语动词用“would (should, could, might) + have + 过去分词”。例如：
If you had taken my advice, you wouldn’t have failed in the examination. 如果你接受我的建议，在这次考试中你就不会失败。
If you have worked hard, you wouldn’t have failed in the exam.
如果你早用功，你就不至于考试不及格了。
3. 表示与将来事实相反的假设时，条件从句的谓语动词用“过去式 / should + 动词原形 / were to + 动词原形”，主句中的谓语动词用“would (should, could, might) + 动词原形”。例如：
If it were to rain tomorrow, the meeting would be put off.
假如明天下雨，会议就会被推迟。
提示：⑴ 用虚拟语气表示条件的条件从句，可以放在主句前，也可放在主句后，但所表达意义的侧重点不同。主句在前时，强调“结果”；从句在前时，强调“条件”。
⑵ 在书面语中有时可省略条件从句中的if，但须将从句中的were, had, would或should放到从句中的主语之前。例如：
Were I in school again, I would work harder.
如果我能再上学，我就会更努力地学习。
Should there be a meeting tomorrow, I would come.
如果明天有会议，我会来的。
Had you arrived at the station ten minutes earlier yesterday, you could have caught the train.
如果你昨天早十分钟到火车站，你就赶上火车了。
⑶ 可用介词短语代替条件从句。例如：
If there weren’t air, there would be no living things.
= Without air, there would be no living things.
如果没有空气，就会没有生命。
【巩固精练】用所给动词的正确形式填空。
1. If it rained, they ___________ (stay) at home.
2. We would be very much pleased if you ___________ (come).
3. What a pity! I haven’t got my car. If I had, I _______ (take) you to the airport.
4. We would answer the questions if we ___________ (can).
5. If I were you, I __________ (take) a long walk before going to bed.
Keys：1. would stay2. came3. would take4. could5. would take