个人愚见:其实是简单的定语从句加省略吧,原句:It may seem strange that someone would put an industrial revolution and two political recolutions into the same packIt 就是形式主语咯 seem 就是系动词strange 就是补语
回答于 1秒前
不用更改,名词从句中,当从句置于句首时才不能用 if,因为怕读者误判为由 if 引导的副词从句,现在已经有 it 代替主语了。