That's what I wrote too,but it's true that we don't really say that in English
Apparently Duolingo has not heard of Gershwin's Porgy and Bess. It didn't like "It ain't necessarily so".
But it allowed "ain't". I consider that a small victory. I had to try it too. :)
For the record, I made the same mistake. But, as I understand it, in that case you would use "verdadero" for such adverbial phrases. While "verdad" and "cierto" and "seguro" in different situations all mean things like "certain"and "true," it seems Duolingo goes for what is more natural to the language, not a non-native speaker's ear.
I was suspicious of DL's use of cierto as "true" until I saw a kid's show in Spanish with a segment called "Cierto o Falso." I said, hey, DL is right after all.
Oh, it's been so long. I believe it was one that featured trivia and segments about animals.
Since subjects are usually omitted, I have forgotten, what is the Spanish word for "it"?
"Not necessarily true" Duolingo didn't accept asca correct answer, and replaced with "It's not necessarily true". Really?
There is clearly a verb, es, in the given sentence, which you should translate, too.
Do native speakers use 'necesariamente' often? I don't mean this in a bad way, but it sounds like a mouthful.
About as often as English speakers use "necessarily", which is not much less of a mouthful. :)
Could this be he/she is not necesarily true, ie faithful or is that meaning for true different in Spanish