虚拟语气

: 最基本的虚拟语气句型:

1. 虚拟现在时表示与现在事实相反的假设，其if 从句的谓语形式用动词的过去式(be 一般用were)，主句用would/ should/ could/ might +动词原形。If places were alike, there would be little need for geographers.如果各个地方都一样，就不需要地理学家了。

2. 虚拟过去时是表示与过去事实相反的假设，if 从句的谓语形式用过去完成时即had＋过去分词，主句用would / should / could / might + have +过去分词。If he had known your address yesterday,he would have telephoned you.

3. 虚拟将来时是表示对将来实现的可能性很小的或不确定的假设。If从句的谓语形式用一般过去式或用were to / should +动词原形，主句用would / should/could/ might +动词原形。If he were to leave today, he would get there by Friday

4. 省略if 采用倒装语序的条件句。有时可以把含有助动词、情态动词、be或have的虚拟条件句中的连词if省去，而将had , should, were 等词提到主语之前，即用倒装结构。If he had worked harder, he would have got through the exams.==>Had he worked harder, he would have got through the exams.If he were to leave today, he would get there by Friday.==>Were he to leave today, he would get there by Friday.If I were in your place, I wouldn’t do that.==>Were I in your place, I wouldn’t do that.

5. 有时虚拟条件句并没用if 从句表示出来，而是用介词短语(otherwise, or, without, but for)、上下文或其它方式来表示。如：We didn't know his telephone number; otherwise we would have telephoned him. Without you help, I wouldn’t have achieved so much. But for （“要不是......”的意思）your help, I would not have succeeded.

II: 虚拟语气在从句中用should的情况:

1. 在表示建议,要求,命令,想法的动词后的从句里, 用should + 动词原形, should 可以省略. 如 advise, agree, command, decide, demand, determine, grant, indicate, insist, order, prefer, propose, request, require, stipulate, suggest, urge, vote.常考到的是: suggest, advise, demand, require, propose, insist, order, request.

His doctor suggested that he (should) take short leave of absence. The author proposed that TV (should) be turned off at least one hour every day.