请各位赐教！

shala

1 It is as difficult to prevent crimes against property as those that are against a person.
  A those that are against a
  B those against a
  C it is to prevent those against a
  D preventing those against a
  E it is against a
答案为C。如果有选择为“to prevent those against a”，是不是更好？
2 Never before had taxpayers confronted so many changes at once as they had in the Tax Reform Act of 1986.
  A so many changes at once as they had in
  B as many changes at onve as they confronted in
答案为B。但A为什么不对？never在句首表否定，可以用so.

joywzy

1,C好，平行并列，做题应从五个选项中选最优的，但有可能答案本身并不perfect.

2，in the Tax Reform Act of 1986=》 时态一般用过去时，而不用过去完成时。
在比较两个人（事，程度等）在某方面相同时，用as...as ;不相同用not so/as...as，所以C，D在这方面的表达均可。

Louisa_xy

第二个as后面的it is 是必需的
第一个it指的是to prevent crimes against property，第二个it 指的是to prevent those against a person
to prevent crimes against property is as difficult as to prevent those against a person.