![Eighteen parts per million.
Eighteen parts per million.](https://content2.mcqstudy.com/ss/tbbt-8-9-00:07:44.290.jpeg.webp)
Eighteen parts per million.
The Big Bang Theory Season 8, Episode 9
![Eighteen years ago,
I sent the FBI Crime Lab samples...
Eighteen years ago,
I sent the FBI Crime Lab samples...](https://content2.mcqstudy.com/ss/tbbt-4-7-00:07:40.823.jpeg.webp)
Eighteen years ago,
I sent the FBI Crime Lab samples...
The Big Bang Theory Season 4, Episode 7
![If you would just let me.
Eighteen months.
If you would just let me.
Eighteen months.](https://content2.mcqstudy.com/ss/bb-2-12-00:27:27.353.jpeg.webp)
If you would just let me.
Eighteen months.
Breaking Bad Season 2, Episode 12
![Eighteen kilometers per hour.
Eighteen kilometers per hour.](https://content2.mcqstudy.com/ss/mm-3-8-00:26:55.250.jpeg.webp)
Eighteen kilometers per hour.
Money Heist Season 3, Episode 8
![--eighteen, 19 and 20.
--eighteen, 19 and 20.](https://content2.mcqstudy.com/ss/bb-5-11-00:43:43.995.jpeg.webp)
--EIGHTEEN, 19 and 20.
Breaking Bad Season 5, Episode 11