![NARRATOR:
Previously on The Big Bang Theory:
NARRATOR:
Previously on The Big Bang Theory:](https://content2.mcqstudy.com/ss/tbbt-8-1-00:00:04.128.jpeg.webp)
NARRATOR:
Previously on The Big Bang Theory:
The Big Bang Theory Season 8, Episode 1
![Previously on
The Big Bang Theory...
Previously on
The Big Bang Theory...](https://content2.mcqstudy.com/ss/tbbt-12-18-00:00:03.003.jpeg.webp)
Previously on
The Big Bang Theory...
The Big Bang Theory Season 12, Episode 18
![Um, it used to be string theory,
now it's dark matter.
Um, it used to be string theory,
now it's dark matter.](https://content2.mcqstudy.com/ss/tbbt-9-8-00:10:33.342.jpeg.webp)
Um, it used to be string THEORY,
now it's dark matter.
The Big Bang Theory Season 9, Episode 8
![that we came up
with this theory.
that we came up
with this theory.](https://content2.mcqstudy.com/ss/tbbt-12-21-00:02:17.789.jpeg.webp)
that we came up
with this THEORY.
The Big Bang Theory Season 12, Episode 21