请分析一下这句话（重点是开头as的用法，这里为什么要用as。）

Question

As has been stated in the annual white book, our national defense per year is well below the average of developed countries.
重点是开头as的用法，这里为什么要用as。

Answer 1

这里的as是正如的意思，是一个指示代词，相当于一个定语从句！具体可参见http://wenku.baidu.com/view/07d05de8551810a6f52486e5.html
因此，这句话可大致理解为“正如年度白皮书所述，我国每年的国防低于发达国家的国防水平。”
仅供参考，望能帮助到你，呵呵！

Answer 2

是病句,没错. 但可以改善:
As has been stated in the annual white book, our national defense [expenditure] per year is well below the average [spending] of [the] developed countries.

"As"=就如; 就像...本回答被网友采纳

Answer 3

as在这里是表原因的 在这里引导的也是 时间状语从句