这个问题，想说说理解，但是，不知对错。如果错误，敬请网站大咖老师们，及时改正。对于这个问题，我比较享受思考过程，对错不重要。

首先，“as+过去分词”结构置于名词（短语）后，作后置定语的情形比较常见。例如：

the facts as observed

the books as listed below

the answers as given at the end of this book

“as+过去分词”结构可以作后置定语。如果，按照这个思路，是否可以猜测一下：“as+过去分词”结构，可以作状语，语意上为比较状语？

如果这样，As reported by a local newspaper解释为比较状语，置于句首，开门见山，是句子的主位，逗号后的分句是述位，是语意的核心。

As reported by a local newspaper, Bailey was more than two-thirds of the way through her race when a runner in front of her began crying in pain.

语意理解为：

As (it was) reported by a local newspaper (that she had been),Bailey was more than two-thirds of the way through her race when a runner in front of her began crying in pain.

这个句子，我全当了语法游戏，不计对错，态度却是认真的。老师们得计对错，对网友负责。

As (was省略)reported by a local newspaper【非限制性定语从句】// , Bailey 【主语(1)】// was 【系动词(1)】// more than two-thirds of the way through her race【表语(1)】//  when【连词】//  a runner in front of her【主语(2)】//  began 【谓语动词(2)】// crying in pain【宾语(2)】// . 

参考译文:正如当地一家报纸报道，当贝利跑到比赛的三分之二以上路程的时候，她前面的一名赛跑选手开始痛苦地哭泣。

备注:as引导非限制性定语，as指代后面整句话的内容，并在非限制性定语从句作主语。关系代词as后面省略助动词was。被限制性定语从句使用被动语态。

【1】从句:As (was省略)reported by a local newspaper

【2】主句: Bailey was more than two-thirds of the way through her race when a runner in front of her began crying in pain. 

备注:主句里面有连词when=at this/that time 引导以下2个并列句

并列句(1):Bailey was more than two-thirds of the way through her race

并列句(2):when a runner in front of her began crying in pain. 

特别备注以下两点:

【1】在as引导非限制性定语从句，如果as在定语从句作主语，且主语是谓语动词动作承受者，则必须使用被动语态as is/was+过去分词结构，其中助动词is/was可以省略。

As is said above, we must protect our earth.正如上面说的,我们必须守护我们的地球。

备注(1):as指代we must protect our earth.

备注(2):as在非限制性定语从句作主语，为定语从句中谓语动词动作承受者，所以定语从句使用被动语态。

【2】在as引导非限制性定语从句，如果as在定语从句作宾语，则使用主动语态结构

As we all know, the earth is round.正如我们所知道的,地球是圆的。

备注(1):as指代the earth is round

备注(2):as在非限制性定语从句中作谓语动词know的宾语，所以非限制性定语从句使用主动语态。