to be lost in deep thought; to be deeply immersed in thought
to be absorbed in reading; to get lost in reading; to be immersed in (a book)
to be absorbed in thought; to muse; to muse about; to think things through
to be lost in thought; to be immersed in reverie
be absorbed in deep thought; be sunk in thought
to be absorbed in reading; to get lost in reading; to be immersed in (a book)
to be lost in deep thought; to be deeply immersed in thought
to be absorbed in thought; to muse; to muse about; to think things through
to be lost in thought; to be immersed in reverie
be absorbed in deep thought; be sunk in thought