老师好！

最近在学习英语的过程中对于过去分词做非谓语动词理解不够透彻，请老师指导！

1. Now,dressed as a guard, he walked boldly into the camp.

=Now, when he was dressed as a guard, he walked boldly into the camp.

本句中dressed为非谓语动词，我理解为因be dressed as（穿着某种不同于自己身份的服装）此结构而用done的形式。

解答：以上属于过去分词作时间状语，可以改为相应时间状语从句

2. Dressed up as Father Chrismas and accompanied by a "guard of honour" of six girls, he set off down the main street of the city riding a elephant called Jumbo.

=When he was dressed up as Father Chrismas and accompanied by a "guard of honour" of six girls, he set off down the main street of the city riding a elephant called Jumbo.本句中dress up as(打扮，盛装打扮)，dressed up as为谓语动词，实则是与 Father Chrismas关系为被动，而非与主句主语关系为被动，为什么首先考虑就近的名词 Father Chrismas的关系？而不是与主句主语的关系。

解答如下:用法同上

你的两个句子中的 dressed up 的逻辑主语都是句子主语，即：

1. Now, dressed as a guard, he walked boldly into the camp.

句中过去分词短语 dressed as a guard 的逻辑主语是 he。

2. Dressed up as Father Christmas and accompanied by a "guard of honour" of six girls, he set off down the main street of the city riding a elephant called Jumbo.

句中过去分词短语 dressed as Father Christmas 的逻辑主语是 he，不是Father Christmas。

补充解答：

这里之所以用过去分词，不用现在分词，是因为 dress 为及物动词，它后面需要有宾语，否则就要用被动语态。如：

He dressed himself as a woman.  他打扮得像个女人。

He was dressed as a woman.  他打扮得像个女人。

如果用于非谓语动词，显然就应用过去分词。如：

Dressed as a woman, he was mistaken for the child’s mother. 他打扮得像个女人，所以被误认为是这个孩子的母亲。