請問這句：She was so beautiful walking into the church.,請問walking是主詞補語，或分詞片語或受詞補語，又或者是分詞構句變來的?請知道的大大為我解惑，謝謝～^_^?

這句有兩種看法ㄟ
看是要把它看成分詞構句，還是形容詞片語
以分詞構句來看的話，原句應該要是：She was so beautiful who was walking into the church.
然後因為前後兩句的主詞一樣(都是she)，所以「who was」可以省略
再加上這句的主詞「她」是以「主動」的方式走進教堂，所以寫作walking
所以分析後的句子應該是：She was so beautiful （who was） walking into the church.
那如果是以形容詞片語來看的話就簡單多了
首先，它本來應該是兩個分開的句子
１　She was so beautiful.
２　She was walking into the church.
然後因為兩個句子的主詞都是同一人，所以可以合併
這時候把第2句換成形容詞的形式
所以walking into the church的意思在這時是翻成：正在走入那個教堂「的」

以上，希望我的解釋妳可以了解^-^

She was so beautiful walking into the church.
= She was so beautiful (as she was) walking into the church.

walking into the church 在這裡是省略 as she was，屬於副詞性質的分詞構句。表示在她步入教堂的「當下」，她很漂亮。

將這個分詞構句移到句首，結構會更明顯：

As she was walking into the church, she was so beautiful.
= Walking into the church, she was so beautiful.

當然，板主在另一回答的意見欄中所寫：

She, who was walking into the church, was so beautiful. 也是正確的寫法，但這是另一種全然不同的寫法，若要省略 who was，前後逗號還是必要的：

She, walking into the church, was so beautiful.

但無論如何，它是不可能省略成 She walking into the church was so beautiful. 的，並且如此一來，它也不是原句用來表達「時間」的寫法，而是用來形容她本人當時的狀態。

這句少了—亇逗号，以致文法錯誤，全句為She was so beautiful, walking into the church. 其中walking 所引導分詞片語当副词修飾其前主要子句

******** following is copied from internet for your reference *********
https://www.ego4u.com/en/cram-up/grammar/participles

In English, participle phrases are mainly used in writing in order to put a lot of information into one sentence.
When shortening or combining clauses with a participle construction, keep the following rules in mind:
- Both clauses should have the same subject.
- The less important part becomes the participle phrase. Important information should always be in the main clause.
- Make sure, you use the correct participle form (see above).
- The conjunctions as, because, since and relative pronouns who, which are left out.
- The conjunctions before, when are used in the participle phrase.
- The conjunctions after, while can be used or left out.