谁给分析一下这句英文倒装句的结构because at no previous time has American security been as seriously threatened from without as it is today.来自 Roosevelt 1941年的国会演讲
问题描述：
谁给分析一下这句英文倒装句的结构
because at no previous time has American security been as seriously threatened from without as it is today.
来自 Roosevelt 1941年的国会演讲
答
at no previous time 属于否定词提到句首,采取部分倒装,正常语序为:because American security has been as seriously threatened from without at no previous time as it is today.