19. The machine-readable medium of claim 10 wherein said determining of the presentation duration of the one of said subject matter and said query or instruction that is presented in (i) comprises measuring a duration of both (i) and (ii).
10. The machine-readable medium of claim 3 wherein said display mode requires the other of said subject matter and said query or instruction that is presented in (ii) to be presented cumulatively with the one of said subject matter and said query or instruction that is presented in (i).