虚拟条件句难点巧掌握

李　芹

虚拟语气作为高考难点一直让许多学生头痛不已,非真实条件句中虚拟语气的考察更是重点.许多语法书上对虚拟的讲解总是涉及时态,笔者认为这极不利于学生对此知识点的理解与运用. 笔者在教学实践作了一些尝试，起到了不错的效果。

一、抛开时态学虚拟

张道真实用英语语法对虚拟语气的定义如下: 在表示一种纯然假想的情况或主观愿望时,动词需用一种特殊形式,成为虚拟语气. 时态与时间有密切关系,而虚拟语气实际是对真实情况的假设,因此其表达方式必须与正常时态的表达有区别.因此,抛开时态,把其作为一种特殊表达方式来理解更容易掌握其规则.如下表中，用had done 结构表示对过去事实的虚拟表达，而不用过去完成时这一概念。因此，在学习虚拟语气时，牢记三个时间段：过去，现在和将来。

以下句为例：She would have said more if he _______(walk) away. 从would have said可看出整个句子时间为过去，因此，按照规则，空格处应为had done结构，再结合句意，应为否定，最终正确答案had not walked 就表达出来了。

二、善于发现含蓄的条件

许多同学误以为虚拟条件只有if可以引导，其实不然。

1. without, but for 可引导相当于的if条件。例：

But for your help, I couldnt have succeeded.等于If you hadnt helped me, I couldnt have succeeded.

2. or, otherwise 相当于if条件。例：

He hesitated for a moment before kicking the ball, otherwise he would have scored a goal. 此题中，otherwise 就等于if he hadnt hesitated.

3. 真实情况暗含的虚拟条件

虚拟语气的表达十分灵活，学生要善于发现真实情况下暗含的言外之意。同一个句子中，既有虚拟语气，又有陈述语气。例：

I would go to the concert but I have no time. 从I have no time 可知其言外之意if I had time, I would go to the concert..

4. 从句也可用if it were not for /if it had not been for（若不是）来构成谓语。

If it were not for your help, we would be in serious trouble.

If it had not been for your help , we would have been in serious trouble.

三、倒装问题的解决

虚拟语气中倒装问题一直是高考热点，也是学生易错的题型，实际上，既然可以倒装，就可以不倒装，许多同学更习惯读不用倒装的句子，即用陈述语序表达的句子。例：

Should it rain, I would stay at home tomorrow.此题中should一词令许多同学出错，而在下句中 If it should rain, I would stay at home tomorrow. 却很少有同学出错。

再如：______ I in your position, I would go.先变为 If I were in your position, I would go。再进行倒装，就容易多了。因此，看到倒装题时，先变为陈述句。

四、虚拟还是不虚拟

有时可以用虚拟语气，也可以不用虚拟语气，两种情况有时同时考察到。主句的谓语有时可用祈使语气，或用陈述语气。例：

If it should rain tomorrow, we would not go shopping. 也可以用下句表达

If it rains tomorrow, we will not go shopping.

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