I wish I were young.我要是年轻就好了。

I wish I could swim.我要是会游泳就好了。

(2)表示过去不能实现的愿望，并对此感到遗憾或后悔，谓语用过去完成时。

I wish you had written to him.我希望你写信给他了。

(3)表示将来的愿望，谓语用would/could/might＋动词原形，实现的可能性较低，接近一种客气的请求。

I wish you wouldn't smoke any more.

我希望你不再抽烟了。

I wish he could come tomorrow.我希望他明天能来。

2．(1)if only后的从句中，表示现在的愿望，谓语常用过去时。

If only mother were here now!现在要是妈妈在这里就好了！

(2) 表示过去不能实现的愿望，并对此感到遗憾或后悔，谓语用过去完成时。

I have failed in the exam.If only I had followed your advice！

我考试没及格。要是我听了你的建议就好了！

(3)表示将来的愿望，谓语用would/could/might＋动词原形。

If only it would stop raining！要是雨能停就好了！

3．在would rather后的宾语从句中，谓语常用一般过去时表示现在或将来的情况；用过去完成时表示过去的情况。

I would rather I hadn't been to such a place.

我宁愿我没有去过那样一个地方。

4．在"It is (about/high) time＋(that)．.."结构中，that从句的谓语用过去式，有时也可用"should＋动词原形"形式，should不能省略。

It is high time that we fought/should fight against the haze.是我们该同雾霾开战的时候了。

Ⅰ.单句语法填空

1．If we had caught(catch) the flight yesterday，we would be enjoying our holiday on the beach now.(2018·天津)

2．There is a good social life in the village，and I wish I had(have) a second chance to become more involved.(2018·江苏)

3．If the new safety system had been put(put) to use，the accident would never have happened.(2017·北京)

4．-Do you have Betty's phone number?