【问】 在非真实条件句中，可以用三种形式来指将来时间：1.过去虚拟式.2. should+不定式，3. were to+不定式。请问，它们之间有何区别?

【答】 根据美国语言学家G. O. Curme的解释，三者的基本意义是相同的，区别点只是表现在可能性的大小上。过去虚拟式表达的可能性最大，should+动词原形次之，were to+动词原形表达的可能性最小。

1. If it rained /should rain/were to rain tomorrow. I wouldn't go.

如果明天下雨，我就不去了。

2. If we missed/should miss/were to miss the train we should have to wait an hour at thestation. (Curme)

如果我们误了火车，我们就得在车站上等一个小时。

3. If he should fail，I would help him.

如果他失败，我会帮助他的。

4. If the sun were to rise in the west，I would not do so.

如果太阳从西边出来，我就不干这个了。

5. What would you do if war were to break out? (PEU)

如果战争爆发，你怎么办呢?