as he was absorbed in the book,he did not notice my entering the room 才对吧
因为他全神贯注的在看书,所以没有注意到我进入房间了.
as连接2个句子的关系词,是because的意思,表示因为.引导一个原因从句,
be absorbed in sth 表示沉醉于...痴迷于...全神贯注的意思.