Looking on the internet deeply has found these results:

i doubt if that's true. is the most popular phrase on the web.

I doubt the found anything 10 results on the web	i doubt if that's true. 146 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
It doesn't look like this phrase is very popular! The search could not find any examples on the internet.	Sep 4, 2015 ... At this point I have little to lose, but I doubt if that's true of you. We live in a divisive era. Our views on partisan politics and a broad range of�... I doubt if that's true. There are quite a number of idiots of all nationalities everywhere. Since India has a large population, im guessing what you are seeing is a�... Apr 9, 2015 ... I doubt if that's true. Recently, we had a universally acclaimed movie about traveling through wormholes (Interstellar), three franchises about�... ... but I bet there are a few that are one generation removed. I doubt if that's true on Earth. Everyone on the ground had to worry about the very basics of survival.

I doubt the found anything

10 results on the web

i doubt if that's true.

146 results on the web

More popular!

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

Sep 4, 2015 ... At this point I have little to lose, but I doubt if that's true of you. We live in a divisive era. Our views on partisan politics and a broad range of�...
I doubt if that's true. There are quite a number of idiots of all nationalities everywhere. Since India has a large population, im guessing what you are seeing is a�...
Apr 9, 2015 ... I doubt if that's true. Recently, we had a universally acclaimed movie about traveling through wormholes (Interstellar), three franchises about�...
... but I bet there are a few that are one generation removed. I doubt if that's true on Earth. Everyone on the ground had to worry about the very basics of survival.