An external confirmation （主语：外部确认）represents （谓语动词：是指）audit evidence （宾语：审计证据）obtained by the auditor as a direct written response to the auditor from a third party, in paper form, electronic form or by other medium.（audit evidence 的定语）

1. 句子主干：An external confirmation represents audit evidence （外部确认是指审计证据）

2. 其余部分是过去分词短语作定语。

（1）用 obtain 的过去分词表示被动，因为 audit evidence 与 obtain 是被动关系。

（2）as a direct written response to the auditor， 指 an external confirmation 的身份性质，作为此种身份而被 obtained。

（3）from a third party，是obtained 的来源。

（4）in paper form, electronic form or by other medium，是obtained 的方式。

An external confirmation represents audit evidence obtained by the auditor as a direct written response to the auditor from a third party, in paper form, electronic form or by other medium.

【翻译】外部确认是指审计师从第三方获得的审计证据，此证据是以书面形式、电子形式或其他媒介直接向审计师作出的书面答复。