"What is that object?"

[fr33th]

Can anyone explain why are we not using the same ending for ki/ti here? If both relate to the same object I'd assume the endings are the same.

[vikungen]

Because tio can never stand in front of a noun.

Tiu objekto, but never tio objekto.

If it is on it's own, then you would use tio.

Tio estas mola. (That is soft)

Tiu lito estas mola. (That bed is soft)

[fr33th]

Thanks for the explanation. So tio can only be used when the subject is unknown. And we use tiu here to emphasise that among all of the objects the question is about that particular one.

[vikungen]

Yes.

[reyley1014]

Why would i not use kiu here? Would i only use it if the sentence was: what object is that object? As far as i can tell in both cases it is clear that we are referring to a specific object so stating it twice is redundant, I'm confused as to why tiu is wrong..

[salivanto]

For the same reason that you wouldn't say "which is that object."

[dotevo]

Why kio tiu objekto estas is wrong?

[salivanto]

It's funny. I'm nearly certain that this is a reference to "Mazi en Gondolando" when Reĝo is trapped in the computer and Mazi wants to help. Reĝo says "Kio estas tiu objekto."

The original English version of that sentence was "what's that green thing?"

[johaquila]

• Kio estas tiu objekto? - What is that object?
• Kiu estas tiu objekto? - Which is that object?
• Kio estas tiu? - What is that [object]?
• Kiu estas tiu? - Which is that [object]?
• Kio estas tio? - What is that [mess]?

The variant "Kiu estas tio?" doesn't seem to make any sense.

I think this would be a lot easier to understand if English had a demonstrative thich contrasting with that in analogy to which contrasting with what. As this is not the case, it may help to think of it this way:

• kiu = which one
• tiu = that one
• ĉiu = every one
• iu = some one
• neniu = no one

I wrote it in two words in all cases as a reminder that unlike ordinary English everyone, someone, no one, but like which one and that one, -iu can refer to specific objects as well as people.

[salivanto]

The TI- correlatives are generally things you can point to. That person, this time, that big. The correlatives that end in -O are sort of nouny.

So, "what is that" is "kio estas tio." We're talking about a noun-like thing and we can point to it.