— What do you think of French?  

— In my opinion, French is _______ English  [ ]

A. a subject so difficult as    

B. as difficult a subject as  

C. as a subject difficult as    

D. difficult as subject as

由于非线性编辑系统的信息存储位置与接受信息的顺序不相关，盘上所存任何文件均可随时调用或修改，插入内容（），大大提高了（）。