虚拟条件句中I必须用were，有用was的情况吗

虚拟条件句中I必须用were，有用was的情况吗

没有见过哟。
1.表示与现在事实相反的假设时，条件状语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”。如：If John had enough money, he could go out of the U.S.如果约翰有足够的钱，他就会离开美国。
If I were in your position, I would accept their offer.如果我处于你的位置，我就接受他们的提议。
2.表示与过去的事实相反的假设时，条件状语从句的谓语动词用“had+过去分词”，主句中的谓语动词用“would(should, could, might)+have+过去分词”。如：If you had taken my advice, you wouldn't have failed in the examination.假若你听从我的建议,你就不会考试不及格了.
If I had known your address, I would have written to you.假如我知道你的地址，我早就给你写信了。
3.表示与将来事实相反的假设时，主句中的谓语动词用“would(should, could, might)+动词原形”，条件从句中用“were to (should)+动词原形”，如：If the sun were to rise in the west, I would follow you.假如太阳从西边升起，我就听你的。
If he should come tomorrow, we would be greatly surprised.要是他明天来了，我们会大感惊讶。
4.当条件状语从句表示的行为和主句表示的行为所发生的时间不一致时，动词的形式要依据它所表示的时间来调整。如：If you had taken the medicine yesterday, you might be well now.如果你昨天吃了药, 你的病今天也许就好了。
If he had taken my advice, he would be a scientist now.如果当时他听了我的劝告, 现在他应该是个科学家了。
5.以上句型可以转换成下列形式：
① 省略if用“were, had, should+主句”。如：Were I in school again, I would work harder.假若我再上学的话，我会更加努力学习。
Had you been here earlier, you would have seen him.要是你早点来的话，你就会见到他。
但在虚拟条件状语从句中，省略连词的倒装形式的句首不能用动词的缩略形式，如我们可以说：Were it not for the expense, I would go to Italy.但不能说：Weren't it for the expense, I would go to Italy.
② 用介词短语without, but for代替条件状语从句。如：　Without air, there would be no living things. 没有空气，就没有生命。
But for your help, I couldn't have made so much progress.要不是你的帮助，我不可能取得这么大的进步。

需要吧