He still enjoyed the movie, though he had already read the book.

though 是连词，表示"虽然、尽管"，用于引导让步状语从句，表达与主句意思相对或矛盾的情况。though 引导的从句可以放在主句前或主句后，放在主句前时通常用逗号与主句隔开。