文中的 lost 在此用作形容词（不是过去分词），注意这里有三个形容词短语并列：absorbed in…, deep in…, lost in…虽然三个形容词短语所用的形容词不同，但意思大致相同，都表示“投入的”“沉迷的”及类似的意思。

Ann was completely lost in her book. 安完全沉浸在她的书里了。

Richard is totally absorbed in his book. 理查德聚精会神地看着书。

She sat, not listening, but deep in thought. 她坐在那里，并没有听，而是在沉思。

Adults are portrayed (描绘) alone in many settings and poses —absorbed in a volume, deep in thought or lost in a moment of leisure.

【备注】absorbed(adj.专心致志,全神贯注的) 和lost(adj.陷入沉思的,迷路的)都是由“过去分词转换”成“形容词”已经失去了动词含义。可直接当形容词使用。

She seemed totally absorbed in her book.她好像完全被这本书迷住了。

After hearing the news,he was lost in thought．听到这个消息后，他陷入沉思。

The teacher told the students to keep together and not to be lost in the woods.  

老师叫同学们在树林里保持在一起,不要迷路。