I said "Using books is fun." Isn't that also a possibility? LOL.
Without more context, you could definitely say so
I sometimes use a book as a tray for food.
ㅠㅠ 재미있지만 어려워요...
Writing THE book counted as incorrect.
'THE' indicates 'specific or fixed thing or things. In that case, 그 is needed.
Aaahh it marked "fun" as wrong.
"writing a book is fun" was counted as wrong...what?
It wasn't hard to find the right combination of English words, but most would say "writing books is fun" rather than this awkward translation.
Why book is wrong ????? 책들 books !
I think you can't write two books at the same time^^
Especially when it's for a 500$ giveaway in Duolingo
If there is already an object marker in the -는 것 clause, does that mean that you can only put 은/이 on 것?
Here is a counterexample to what you're probably thinking: 책을 읽는 것을 싫어합니다.
However, in all honesty, I'm not sure exactly what you're asking.
것 can take whichever maker is necessary to the sentence's meaning (object, subject, or topic).