If I + V-ed, I would
结构︰If+过去式动词，主词+过去式助动词（would/should 等）+原形动词
说明︰这是与现在事实相反的假设句型。if 子句中的动词，不论主词为第几人称，一律用 were，were 可置于主词前面，而省略 if.过去式助动词除用 should（用于第一人称）、 would（用于第二、三人称）外，还可用不分人称的 could，might 和 ought to，它们与动词原形结合起来构成假设语气.
If I knew his address, I could write to him.
如果我知道他的住址，我会写信给他。
If I were free now, I might call on him.
如果我有时间，我可能会去看他。
If you were in my shoes （=Were you in my shoes）, what would you do?
如果你站在我的立场，你会怎么做?
Were I rich enough, I would buy a sports car.
如果我有足够的钱，我就买一辆赛车了。
How happy I would be if I were a few inches taller!
要是我再高几寸，我会好高兴。
If I had a car, I could take her for a drive.
如果我有车， 我就带她去兜风了。
If I had binoculars, I could see that comet clearly.
如果我有望远镜，我就可以清楚地看见那颗彗星。