If 条件句中的虚拟语气
(一)对现在的虚拟
从句：did(虚拟语气中be→were)
主句：would(should, could, might)+do
If Isaw him now，I would be very happy.
(二)对过去的虚拟
从句：had+done;
主句：would(should, could, might)+have+done
If it had not rained yesterday, we would have played football.
(三)对将来的虚拟
从句：should+do/were to+do/did;
主句：would(should, could, might)+do
If it were to snow/should snow tomorrow，we would cancel the 1000-meter race.
(四)混合的虚拟语气
从句发生的动作和主句发生的动作，不在同一个时间范围内发生。
If he were alive now, he might have finished his scientific researches on the bridge building three years ago.
如果他现在还活着，他可能三年前就完成了他的桥梁建筑科研工作了。
If it had not snowed yesterday, we would be on the way to Shanghai.
要是昨天不下雪的话，我们现在就应该在去上海的路上了。
【例】( ) we introspect ourselves, the better we will understand ourselves.
A. The more frequent
B. The frequenter
C. The more frequently
D. The frequentlier
【答案】C。此题结构为：the----,the---，表示：越…，越….。句意：“我们自省的越频繁，我们就会越了解自己。”题干中填入的是需要修饰动词introspect，结合词性特点可知需要用副词。所以正确答案是选项C。
【例】If you ( ) in such a hurry, you ( ) sugar into the sauce instead of salt.
were not, would not put
were, would put
had been, would have put
had not been, would not have put
【答案】D。根据句意，如果你不那么着急，就不会错把糖当作盐放进蘸料里面了。我们可以看出，这里需要使用虚拟语气，表示对一般过去的假设。从句用had done, 主句用would have done。本题中，主句和分句都需要用否定的语气，故此题选择D项。
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