guess this 70's sitcom from 2 words in the them song

I recall them being played in the show's very first episode, and they probably used the full tune a few more times during the first season. But it was cut back to the one most viewers recall very early in the show's run.

EDIT: Here's the theme tune for season 1 with lyrics, and then for S2, the lyrics that were used for the remainder of the show's run:

www.lyricsondemand.com/tvthemes/marytylermooreshowlyrics.html