As I said first time around:
Japanese doesn't really use plural nouns, but employs an element known as a counter. There's a bunch of different counters that apply to different types of thing.
As a rough example, in English you would say one pen, two pens. In Japanese it would be ippon pen, nihon pen* - meaning one cylindrical object† that is pen, two cylindrical object† that is pen (pon/bon/hon being the counter for cylindrical objects†). One CD, two CDs would be ichimai CD, nimai CD - one broad flat thing (mai) that is CD, two broad flat thing that is CD. And so on.
I'd need to listen to the original and remember what the counter for races is (tracks would be pon/bon/hon; no idea what race events would be and even if Idid learn it once it was 30 years ago), but you'd be listening out for "nan" before the counter to mean "some", rather than "ichi" (possibly modified to "i" depending on the counter: ichi+pon = ippon, like the pen example) to mean "a".
*Although that's more emphasising the quantity. Used in a sentence where you're referring to the pens it'd be "pen (o) nihon"
†It's actually "long, thin objects", but pens are the archetype. Also I have a core memory of my very lovely Japanese teacher trying to say the word "cylindrical" when we were doing counters, which was technically my fault; sorry Keiko.