If的真实与非真实条件句在语境中的运用

        谈到If的条件句，同学们的反应是不是“主将从现”，即“主句用一般将来时，从句用一般现在时”。那么首先恭喜大家基础知识都掌握的非常牢固。但是，会认、会翻译不等同于会用，今天我们来完成这个从会认到会用的过程，具体看看两种If的条件句及我们会在什么语境中用到它们。

        首先，我们来看下面情境对话中的两种回答：

—— 明天在哪下课？

—— 8点半，在武广呢。

—— 哟，这么可怜。我明天下午没什么事。要是有时间的话，就去接你吧。（Situation  I）

—— 哟，这么可怜。我明天下午要出差。要是有时间的话，就去接你了。（Situation  II）

        同学们可以很容易看出在 Situation  I 中，真相是：He is likely to have time. （他很有可能有时间）而在 Situation  II 中，真相是 : He is not likely to have time.（他不太可能有时间）。这两种前提条件下，“要是有时间就去接你”所对应的英文表达就大相径庭：

Situation  I   ：If I have time , I will pick you up.

Situation  II  ：If I had time , I would pick you up.

        这两种If的条件句就分别属于If的真实和非真实条件句（If conditional  real & unreal），即种的条件是真实、很有可能发生的，第二种的条件是非真实、不太可能发生的。

首先，我们把这两种句式的结构放到表格中来对比：

不难发现，种句子就是我们所熟知的“主将从现”的句型，它的前提就是表示真实的，或将来很有可能发生的情况；

而第二种非真实的，将来也不太可能发生的情况，If的从句用一般过去时，主句用到了would ＋动词原型的句子；

了解这两种前提及其结构之后，接下来，我们具体来看看它们的运用语境。

一、If的真实条件句 （Present real conditional）

1. 谈论未来可能发生的事情；

最典型的就是如下问句：

If you are free tomorrow, what will you do ?  （明天你要是有空，你会做什么？）

2.  用于真实情况下的列举。

我们在观点的展开时可以通过列举说明具体情况来支撑观点句，比如留预三级听力中的对话：

—— OK, last question. Can peer pressure be a positive thing?

…

—— （Yes.）Let me explain. If my friends study hard and get good grades in school, I’ll try and do the same. If …

就是通过列举来解释观点；

再举个例子，在回答下面这个问题时：

What are the qualities of a good teacher?

这里，我们可以用If的从句来列举“如果一个老师…（好的品质） ， 那么…（好的结果）” 。

I should say a good teacher is one who is always well prepared for the class.

And I guess if a teacher has a good sense of humor, students will be more willing to follow him in class.

If…

同理，可以用来列举的情况还有：

Do you think it is important for an individual to be on time?  

这里我们同样可以用If的从句来列举“如果…（某一情境） ， 那么…（应该准时）” 。

Yes.

For example, if you know someone is waiting for you, you should try to be on time.（如果你知道某个人在等你，你应该尽量准时）。

二、If的非真实条件句 （Present unreal conditional）

        它可以用来描述想象的、非真实的场景，或表达说话人的建议、愿望、假想等，具体包括：

1. 提供建议；

留预三级的听力材料中，就有这样一段对话：

—— I  want to use the rest of my time wisely . Do you have any recommendations ?

—— If it were me, I’d consider doing some community service. （“如果是我的话，就会考虑做社区服务”。显然这里不是“我”，所以用到了非真实的条件句。另外，请同学们注意这里的be动词，在非真实条件句中，我们用were，不用was。同理，“如果我是你” 对应英文表达为 If I were you.）

2. 表达不太肯能实现的愿望（比如表达羡慕嫉妒）；

如 If I were taller, I would buy that dress.

     If I were in your age,  … 

3. 假想 ：假定场景（如做心理测验）；

同样是留预三级的听力材料中，这样两处：

（1）Susan: Imagine someone is pressuring you to do something you know is wrong. What would your parents do if you told them?

Laila: If I told my parents about it, they’d support me. They wouldn’t get angry or anything. Obviously, they’d be happy I told them.

前面给了前提 imagine… ，则通常表示不真实或不太可能发生。

（2）If I had my way, a vacation would consist of sleeping in late and watching TV.

前提是说话者的妻子选择了beach vacation。

常见的还有如下这些提问：

（1）If you had a child, what leisure places would you go with your child?

I think I would take my child to library and a field as part of leisure activity.

Also, I would travel with my child because in my opinion, a child learns much more from traveling than from any of the textbooks or any motivational videos.

I would …

（2）What would you do if you had the opportunity to travel in the outer space?

I would be the first one who ever set foot on the Mars， 

and I would want to check it out whether there is water or life with my naked eyes.

I would …

（3）What would you do if you saw something valuable but didn't belong to you on the street ?

4. 强调观点。

我们回到前面真实条件句的一个例子：Do you think it is important for an individual to be on time?  

我们前面已经给出了回答及一个if句子的列举：

Yes.

For example, if you know someone is waiting for you, you should try to be on time.

另外，为了强调准时的重要性，我们可以再次表达“如果… (不准时)，那么… (造成的困扰)”。此时，“不准时”这一观点与我们本身的“要准时”是相悖的，所以我们用非真实的条件句，如：

If an individual was late for a meeting or a flight, the person would miss something important. 

熟能生巧，我们再举个例子来熟练运用吧。

下文是一段托福口语的听力笔记总结，学生的课程时间出现了冲突，有解决办法一、二，需要选择一种。

Problem: conflict of class schedule; two required classes are being offered at the same time.

Solution 1: do independent study.

Pro: meet with the professor when needs to.

Con: lack of motivation; might put things off.

Solution 2: take one of the course at another school.

Pro: his school takes the credit, and the course offered at the other school is excellent.

Con: it’s a long drive; waste of money and time.

回答的样本中，选择了第二种解决办法，那种解决办法就是与答案观点相悖的，我们可以用If的非真实条件句“如果do independent study，就会lack of motivation”

I would recommend him to take the course in the other university. Although this will cost him some time and money, he will finish the course. 

Also，he would’t be motivated if he studied independently，this is a good way to motivate him.

        同学们现在会用了吗？