操作方法

• 01

  一、虚拟条件句的基本类型
  
  (1) 与现在事实相反：若与现在事实相反，条件从句的谓语用过去式(be通常用were)，主句谓语用“should (would, could, might)+动词原形”。如：
  
  If we left now, we should arrive in good time. 假如我们现在就走的话，我们就会及时到达。
  
  (2) 与过去事实相反：若与过去事实相反，条件从句的谓语用过去完成时(had+过去分词)，主句谓语用“should (would, could, might)+have+过去分词”。如：
  
  If he had been in that train then, he might have been killed in that accident. 如果当时他也在那列火车上，他可能就死于那场车祸了。
  
  (3) 与将来事实相反：若与将来事实相反，条件从句的谓语用过去式(be通常用were)，主句谓语用“should (would, could, might)+动词原形”。如：
  
  If he went，would you go too? 如果他去，你也去吗？(大概他不会去)
  
  If I asked him，I'm sure he'd help us. 如果我向他提出要求，肯定他会帮助我们。(不过我不打算这样做)

  
• 02

  二、错综时间虚拟条件句
  
  所谓错综时间虚拟条件句即条件从句与主句所指时间不一致，如从句指过去，而主句即指的是现在或将来，此时应根据具体的语境情况，结合上面提到的三种基本类型对时态作相应的调整。如：
  
  If you'd listened to me, you wouldn't be in such trouble now. 如果你听了我的话，你现在也不会有这样的麻烦了。
  
  If you were in better health, we'd have let you go with us. 你要是身体好一点，我们就让你和我们一道去了。

  
• 03

  三、含蓄虚拟条件句
  
  所谓含蓄虚拟条件句即指将条件从句隐藏在上下文一定的短语中的一类条件句。如：
  
  Anybody else would have believed you. 任何别人都会相信你的话了。
  
  Without your help, I couldn't have achieved all this. 要不是有你帮助，我不会取得这些成就。
  
  I would have written before, but I have been ill. 我本想给你写信的，但我生病了。

  
• 04

  四、if it weren't (wasn't) for与if it hadn't been for
  
  这是两个很常用的虚拟语气句型，其意为“若不是(有)”“要不是有”，与but for, without同义。如：
  
  If it wasn't (weren't) for the children, we wouldn't have anything to talk about. 要不是因为孩子们，我们不会有什么可谈的。
  
  If it hadn't been for the rain, we would have had a good harvest. 要不是有雨，我们本会获得一个大丰收的。
  
  If it hadn't been for the doctor's care, I wouldn't have recovered so soon. 要不是医生的照顾，我不会痊愈得这么快。
  
  注：一般说来，if it weren’t (wasn't) for 用于谈论现在的情况，而if it hadn’t been for 用于谈论过去的情况。但实际上if it weren’t (wasn’t) for有时也可用于谈论过去的情况。

  
• 05

  五、使用虚拟语气的特殊句式
  
  (1) I wish…句式：要表示与现在事实相反的愿望，从句谓语一般过去时或过去进行时，表示与过去相反的愿望，从句谓语用过去完成时或would / could+have +过去分词，表示将来没有把握或不太可能实现的愿望，用would (could)＋动词原形。如：
  
  I wish I was ten years younger. 我但愿年轻10岁。
  
  I wish I could speak your language. 但愿我能讲你们国家的话。
  
  I wish I hadn't wasted so much money. 但愿我没浪费这么多钱。
  
  (2) if only…句式：if only 与 I wish一样，也是表示与事实相反的愿望的，其后所虚拟语气的时态与 wish后所接时态的情况相同。如：
  
  If only Tessa was here now. 要是特萨现在在这儿就好了。
  
  If only l knew the answer to your question. 我但愿知道你的问题的答案。
  
  (3) as if / as though…句式：以as if (as though)引导的方式状语从句或表语从句，有时用虚拟语气，若表示与现在事实相反，谓语动词用一般过去时；若表示与过去事实相反，用过去完成时；表示将来的可能性不大，用would (might, could)+动词原形。如：
  
  I felt as if I was swimming. 我觉得好像在游泳似的。
  
  At that time she acted as if I were her servant. 当时她的举止好像我是她的仆人。
  
  (4) it's time…句式：从句谓语通常用过去式表示现在或将来，有时也用过去进行时或“should+动词原形”(较少见，且should不能省略)，其意为“(早)该干某事了”。如：
  
  It's time you washed those trousers. 你该洗洗那条裤子了。
  
  I'm getting tired. It's time we went home. 我累了，我们该回家了。
  
  注：time前有时有about和high修饰：
  
  It's high time we left. 我们早该动身了。
  
  (5) would rather…句式：通常用一般过去时表示现在或将来的愿望，用过去完成时表过去的愿望。如：
  
  I would rather you came tomorrow. 我宁愿你明天来。
  
  I would rather you didn’t mention the price. 我宁愿你别提价钱。

  
• 06

  六、使用虚拟语气的宾语从句
  
  在表示“坚持”“命令”“建议”“要求”等后的宾语从句要用虚拟语气。这些动词主要包括insist, order, command, advise, suggest, propose, demand, require, request, ask等，其虚拟语气格式为“should+动词原形”，其中的should在美国英语中可以省略。如：
  
  The doctor advised that he change his job. 医生劝他换工作。
  
  The detective insisted that he should have a look. 警探坚持要查看。
  
  The seller demanded that payment should be made within five days. 卖方要求5日内付款。
  
  Her uncle suggested that she (should) get a job in a bank. 她叔叔建议她在银行里找个工作。
  
  注意：insist后接宾语从句时，有时用虚拟语气，有时用陈述语气，其区别是：若谓语动词所表示的动作尚未发生，或尚未成为事实，则用虚拟语气；若谓语动词所表示的动作已经发生，或已经成为事实，则要用陈述语气。比较：
  
  She insisted that I (should) stay for supper. 她一定要我留下吃晚饭。
  
  He still insisted that he wasn’t there at the time. 他仍然坚持说他当时不在那儿。
  
  与insist相似，suggest后接宾语从句时，也可用虚拟语气或陈述语气，其区别是：若谓语动词所表示的情况尚未成为事实，则用虚拟语气，此时suggest通常译为“建议”；若谓语动词所表示的情况为既成事实，则要用陈述语气，此时的suggest通常译为“表明”“认为”。比较：
  
  He suggested that we (should) come another day. 他建议们改日再来。
  
  His smile suggested that he was satisfied. 他的微笑表明他是满意的。

  
• 07

  七、使用虚拟语气的主语从句
  
  形容词important, impossible, necessary等后的主语从句通常用虚拟语气。如：
  
  It's impossible that he (should) marry her. 他同她结婚是不可能的。
  
  It's important that he (should) remember this. 他记住这一点很有必要。
  
  注：在It is amazing (strange, surprising, astonishing, a pity, a shame)以及 I am surprised (sorry) 和I regret等结构后的that 从句中有时也用should，表示说话人的惊异、懊悔、失望等情感，常含有“竟然”之意。如：
  
  It's strange that he should come so late. 他竟然来这么迟真是奇怪。
  
  这类句子若用陈述语气，则不带感色彩，比较下面两句：
  
  I'm surprised that he should feel lonely. 我很惊讶他竟感到孤独。
  
  She was surprised that I knew all about it. 这事我全知道她感到惊奇。