Question

Much labor would have been saved if the electronic computers_____________ before.

A. had invented                B. were invented

C. should have been invented   D. had been invented

Answer

D

【解析】

试题分析：考查虚拟语气。句意：如果以前电脑被发明出来，更多劳动力就会被节省下来。本句考查的是if引导的条件状语从句的虚拟语气，当与过去事实相反的时候，从句使用过去完成时，主句使用“情态动词+have+done”。根据句意可知本句使用被动语态，故D正确。

【名师点睛】

本题中考查了if引导的条件状语从句的虚拟语气，其用法简要概括如下：1、表示与现 在事实相反的情况，从句：If主语+过去时(Be动词用were)；主句：主语+should/would/could/might+do： 2、表示与过去事实相反的情况，从句：If主语+had+done；主句：主语+should/would/could/might+have done 3、表示对将来情况的主观推测，从句：①if+主语+were to do②if+主语+should+do ③if+主语+did（动词过去式）/were ；主句：主语+should/would/could/might+do

高考例题：

【2012安徽卷】Grace doesn't want to move to New York because she thinks if she there, she wouldn't be able to see her parents very often.

A. lives B. would live

C. having asked D. Were to live

答案:D

解析:在表示将来的情况下，主句中第一人称可用should，其他人称用would；从句中任何人称都用should,不可用would.此处were to live用于虚拟语气，表示与将来的事实相反。

考点：考查虚拟语气