事实和虚拟假设的混合句，这样的句子不仅仅是时间的不同，而重要是事实和假设的混合。真实条件句的原则叫主将从现，实际是要表示将来。但是其中的主句用正常的将来时，但是从句(条件状语从句和时间状语从句)用的是现在时。时态上整体退了一步，所以虚拟语气也就是在主将从现的基础上再退一步。
例如： If you come over here, I'll share it with you. 表达了一个条件。
I would have gone to visit him in the hospital had it been at all possible, but I was fully occupied the whole of last week. 
该句前半部分是假设虚拟，而后半部分是事实的陈述。 
Your math instructor would have been happy to give you a make-up examination had you gone and explained that your parents were ill at the time. 
该句前半句用的是假设虚拟，后半句主句也用的是假设虚拟（如果你去并且解释的话），但是后半句的从句用的是事实语气，因为“父母病了”是客观事实，故不需要用虚拟形式had been。