白勇语法第6章语法第26练习题，高手帮助

26.it is as difficult to prevent crimes against property as those that are against a person

c.it is against a

e.it is to prevent those against a

我选c,因为to prevent前面已有,可以省略掉.但答案选e,这是为什么呢?

菜鸟飞过~~~我的想法和foreverlei 的想法差不多~

未划线部分it is as difficult to prevent crimes against property ……

其中it是做形式主语，也就是说这句话其实是To prevent crimes against is as difficult as

补充完整：To prevent crimes against is as difficult as to prevent those against a person.

  (平行结构：to do sth is to do sth  ，to do不能省)

再按照题干it作形主的方法补上it is