Tom was found in own room，where he lay dead.句中dead查词典，含义有：

主句+，由where 引导的非限制性定语从句，相当于and there

Tom was found in own room and there he lay and was dead.

人们在自己房间发现汤姆并躺在那里死了.

回答如下：

以上可以从三个方面来理解

以上结构可以从3种方式去理解（dead adj. 死去的)

【1】形容词作方式状语结构理解（可以把dead看作为一个形容词)

Tom was found in own room, where he lay dead

=Tom was found in own room and there he lay by means of being dead

=Tom was found in own room and there he lay and was dead

【2】双重谓语用法结构理解

【动词+过去分词双重谓语结构】

【双重谓语即：兼做系动词的行为动词，在句中即表行为又表状态的双重作用的谓语称为双重谓语.表行为动作发生时主语所处一种状态.】

Tom was found in own room, where he lay dead

=Tom was found in own room and he was dead when he lay there

例如He came home exhausted．

＝He was exhausted when he came home．

【动词+现在分词双重谓语结构】

他回家时已是筋疲力尽。

They lay there chatting．

＝They were chatting when they lay there

他们躺在那里聊天。

He wandered wondering．

＝He was wondering when he wandered．

漫步时，他在冥思。

【3】系动词+表语结构理解（damaged adj. 被损坏的)

Tom was found in own room, where he lay dead .

Tom was found in own room , where he lay dead

【系动词lay+形容词dead】（可以把dead看作为一个形容词)

可以通过以上3种不同理解方式去掌握以上语言现象并灵活运用这种语言现象表达意思。当然最后好要看你喜欢或者习惯用哪种方式去理解了.由你自己决定了.