Why doesn't this accept "That tall woman is not bad!" as an answer?
Since the adjectives are feminine, shouldn't that be a possible translation? And since "The big one" requires a very specific context to be used for a person in English.
And it doesn't accept "That big thing is not bad!" either.
There is no word that means "woman" or "thing" (or anything similar) in the Czech sentence.
You might say that there is also no "one" in the Czech sentence, but I would suggest that we are learning here that "one" can be understood, possibly because it is generic, while "woman" or "thing" is specific and would need to be identified in the original. Perhaps one of the Czech natives on the team will offer a better explanation.
The fact that the "correct" answer includes a supplement — "one" — to make sense in English demonstrates that simply falling back on word-for-word translation — 'There is no word that means "woman" or "thing"...' — is not a good answer to the question I actually asked. You have to add something to make the English translation make sense. So, why is "one" is only possible option?
Basically, I'm assuming that "velká" here is working as a substantive adjective, like in Latin "magnus" on its own means "big man", "magna" on its own means "big woman", and "magnum" on its own means "big thing." Can Czech adjectives work the same way too since they specify both gender, number and case through their endings and do not require a noun to supply the idea "man", "woman", "thing", etc.?
Can "Ta velká" refer to a person? Then, since it is feminine and singular, "woman" or "girl" should be acceptable alternative generic supplements in place of "one." The form of the adjective is the identifier in the original that you claim isn't there.
Can "Ta velká" refer to an inanimate object? From Mod answers earlier, that is definitely a possibility. So, "thing" is just as good and obvious a supplement to add as "one" is.
I'd actually argue that "thing" — or "woman" or "girl", assuming that this can refer to a person in idiomatic Czech — is a better supplement than "one" because "one" requires a context in English that is not supplied in this exercise. When you talk about "The big one" or "That big one", you are picking out one from a pair or small group of similar people or objects and using size in this case to differentiate them. There is no context to show that that is what is happening here.
So, why is "one" the only allowed supplement for translating "Ta velká" in this sentence when there are others that can work just as well?
ta velká - the big (something) - the big one
Yes, it stands on its own, no you should not start inserting the actual thing it could be - the big building (budova)? the big garden (zahrada?) the big thing (věc)? the big person (osoba)?
It is not any noun adjective, it is really a pure adjective. The demonstrative makes it quite clear.
There is simply no reason to insert anything specific. The English "one" is just an auxiliary thing the English grammar requires while other grammars do not.
Die große ist nicht schlecht. not Die große Sache ist nicht schlecht.
But "one" is not an auxiliary that just means "something" in English. In this use it means "one out of a pair or number of items."
"The big one" in English requires a group, category or set to refer to. You use it when you are identifying one particular person, object, idea, etc. out of a number of them. It is not just a random auxiliary thing that you can throw in anywhere. Unless you have some indication from context of what "one" refers to, then it is not functioning properly in English.
Yes, "The big one..." can be good translation, if a context that allows it to make sense is available.
But without it, why is a word that requires that context to make sense chosen as the only available option when a neutral auxiliary word like "woman" (since we know that whatever it is is feminine gender), "person" or "thing" could work equally well?
My issue is not that I'm confused about the Czech sentence. It's that your English translation doesn't work on its own, and so this is a bad question if that's the only possible answer.
On the other hand, if you had a sentence like "Ta velká není špatná, ale ta malá je špatná." that you translated as "The big one is not bad, but the small one is bad." that would be fine, because the sentence itself indicates that you are contrasting two things, whatever they are. (There's probably a better way to write that in Czech, but I'm just using it as an example.)