Ifthenewsafetysystem

问题详情：

If the new safety system _______ to use, the accident would never have happened.

A．had been put        B．were put               C．should be put      D．would be put

【回答】

A

 【详解】

考查虚拟语气。句意：如果这个新的安全系统被投入使用过的话，这个事故就不会发生了。根据主句确定是对过去情况的虚拟，所以从句谓语用had done形式，此外根据句意可知是被动，用被动语态，故A项是正确的。

【点睛】

英语中的三种语气，语气是动词的一种形式，用来说明我们对自己的话所采取的态度。陈述语气（疑问，否定，肯定，感叹）祈使语气（命令，要求，建议，*告）虚拟语气：不可能发生的事，愿望，建议，与事实相反的假设等.虚拟语气在条件中的具体用法真实条件句If you work hard,you’ll surely pass the exam.虚拟条件句（假设情况不存在，实现机会很小）If I were a bird, I could fly freely in the 从句的谓语动词主句谓语动词1.与现在事实相反动词过去式（be一律用were）would/could/might/should+动词原形2.与过去事实相反had donewould/could/might/should+have done3.与将来事实可能相反a.动词过去式（be一律用were）ld+动词原形（不能用would） to+动词原形would/could/might/should+动词原形与现在事实相反if从句：动词过去式（be---were）主句：would/could/might/should+动词原形If we had time, we would go with I were you, I shouldn’t do it weren’t raining, we wouldn’t stay.与过去事实相反if从句：had done主句：would/could/might/should+have doneIf the teacher hadn’t helped us, we couldn’t have succeeded.I could have done it better if I had been more he hadn’t been ill, he might have come.3.与将来事实可能相反if从句：a.动词过去式（be一律用were）        ld+动词原形（不能用would）        to+动词原形主句：would/could/might/should+动词原形If he came tomorrow, I would tell him it should rain tomorrow, I would stay at home and watch it were to snow tomorrow, they would not go ld he come tomorrow, please give the book to him.错综时间条件句在虚拟语气中，有时条件从句动作发生的时间和主句动作发生的时间是不一致的，称为错综时间条件句。这种句子的形式往往要根据句子的时间相调整，分别处理。If you had spoken to him yesterday, you would know what to do you had followed the doctor’s advice then, you would be all right you had watered them more, the crops would be growing still better now.(有时时间会省略）含蓄条件句有时虚拟条件不用if条件从句，而用介词或介词短语来表示。They would not be able to live without him.（如果没有）He would have failed but for his teacher’s timely advice.（要不是）=if it had not been forIf only you had worked with greater care!(要是......就好了）You would have done the same thing in her a little more care you could have avoid the traffic accident.虚拟结合条件句在虚拟语气中，假设的情况有时间可以通过上下文或其他方式表现出来，并且虚拟的情况和真实的情况同时存在。I was ill that day. Otherwise, I would have taken part in the singing competition.（实------虚）=I was ill that day. If I hadn’t been ill that day, I would have taken part in the singing would have bought the piano, but he didn’t have enough money.（虚------实）=He would have bought the piano if he had had enough money, but in fact he didn’t have enough money.省略if倒装条件句在虚拟语气中，if从句假设的情况中如果有助动词had, should和were，那么可省略if，把had, should和were放在句首构成倒装，简称省略if倒装条件句。If he had finished the work yesterday, he would have gone to the concert with you.=Had he finished the work yesterday, he would have gone to the concert with I were you, I wouldn’t do that.=were I you, I wouldn’t do I should meet him, I would tell him about it.=Should I meet him, I would tell him about it.

知识点：过去完成时及其被动式

题型：选择题