Researchers【主语】of the Pleistocene epoch【修饰主语的介词短语(定语)】have developed【谓语,现在完成时】all sorts of more or less fanciful model schemes【宾语(及前面作修饰的定语短语)】of【介词引导介词短语作宾语的定语,后面跟的从句作of的宾语】how【引导词引导宾语从句】they【宾语从句的主语】would have arranged【宾语从句的谓语,虚拟语气,完成时】the Ice Age【宾语从句的宾语】had they been in charge of events【倒装的条件状语从句,过去完成时】.
这句最难懂的是最后一个条件状语从句
had they been in charge of events
这句省略了引导词if.这种j省略必须通过倒置才许可,即把助动词had搬到句首.还原的句子是
if they had been in charge of events
(如果他们决定发生的事件).当然这个条件不可能发生,没有研究者能回到远古时代去决定那时的事件.所以这句是虚拟语气.而这类虚拟语气的条件状语从句,通常省略if而把had放到句首.