虚拟语气如何准确判断是与过去相还是和将来现在相反呢?

虚拟语气如何准确判断是与过去相还是和将来现在相反呢?

虚拟语气可以表示过去,现在和将来的情况,时态的基本特点是时态往后推移.
a.与现在事实相反的假设
则用一般过去时（be用were）should（would）等 +动词原形
例如：If they were here,they would help you.如果他们在这儿,
含义：They are not here,they can’t help you.
b.与过去事实相反的假设
则用过去完成时
should（would）等+ have+ 过去分词
例如：If he had come yesterday,I should / would have told him about it.如果他昨天来的话,我会把这件事告诉他的.
含义：He did not come yesterday,so I did not tell him about it.
c.表示对将来不大可能发生的事情的假想
则用一般过去时
should/would等 + 动词原形
were+ 不定式
should+ 动词原形
例如：If you succeeded,everything would be all right.如果你将来成功了,一切都会好的.
If you should succeed,everything would be all right.
If you were to succeed,everything would be all right.
含义：You are not likely to succeed,everything will be what it is now.
再问： 如果是错综虚拟语气呢
再答： 你高中还是大学？

如果从句和主句都表示过去的，那从句用had done,主句用would ,could,might,should+have done
如：If you had taken my advice,you would not have been late for the meeting yesterday.如果从句表示过去的，但主句表示现在的，从句用had done,主句用would ,could,might,should+do,如：If you had taken my advice,you would not be late for the meeting now.这种一般都有个时间，如果没有表示时间的词也可以从上下文看出。
再问： 高中
再答： 看懂了吗。。
再问： 。。没米。
再答： 英语水平怎么样。130分以上的话建议继续研究。130分以下的话建议会做题就行了不要深究。这在大学里都是一个需要深刻讨论的话题。可以多背背例句。比如说
If it had rained last night, the ground would be wet now. 要是昨晚下过雨的话，现在地面就会是湿的。
You would be much better now if you had taken my advice. 假若你当时听我的话，你现在就会好多了。

条件从句用 if I were…时，既可指现在也可指过去：
If I were you, I would stay. 我要是你我就会留下。
If I were you, I’d go to night school. 我要是你，我会上夜校。
If I were not busy, I would have come. 假若我不忙，我早就来了。
也可用 if I had been you也表示过去：
If I had been you，I’d have taken the job. 我要是你，我就接受那份工作了。