OG153和倒装结构

merit

153. A recording system was so secretly installed and operated in the Kennedy Oval Office that even Theodore C. Sorensen, the White House counsel, did not know it existed.

(A) A recording system was so secretly installed and operated in the Kennedy Oval Office that

(B) Installed and operated so secretly in the Kennedy Oval Office was a recording system that

排除后剩下这两个选项，答案是A,但B除了用倒装结构外也没问题啊。

顺便请大家帮帮忙，一起总结一下倒装结构的用法（论坛里关于这一用法的讨论不多，但前段时间考G的同学都反应考试中涉及这一考点的很多）。

sammen

倒装有2种，全倒和部分倒装。虚拟理if省略时should和had可以倒装。介宾结构在句首要倒装。建议看看刘振敏的语法书。里面说的满具体的。