"Is the flag red or blue?"

Translation: Ĉu la flago estas ruĝa aŭ blua?

[Aderight27]

Why rugas and bluas rather than ruga snd blua?

[vikungen]

estas ruĝa = ruĝas

estas blua = bluas

both are valid, as all adjectives can be turned into verbs like that.

[LouisSepdekdu]

No, all few verbs cannot be turned into verbs like that. I would even say most cannot.

[hellomidnight]

The Esperanto Language Blog has a helpful post about this:

https://blogs.transparent.com/esperanto/adjectives-love-em-leave-em/

[jrzpol]

Why is not accepted "Cu estas la flago ruga au blua?"? Is it wrong?

[hellomidnight]

Ĉu la flago estas ruĝa aŭ blua = Is the flag red or blue?

Ĉu estas la flago ruĝa aŭ blua = Is it the red or blue flag?

[Rae.F]

Wouldn't the second question not take the definite article?

[hellomidnight]

Yes it would, thank you for noticing the error. I've corrected it.

[GaelgAboo]

La flago estas verda kaj blanka!

[alkomaro]

la Ordo de la vortoj ne Estas grava en Esperanto Ĉu la flago Estas.. = Ĉu estas la flago..

[StephieRice]

That is not true.
For verbs like 'esti' the order matters very much as there is no way to denote an "object" for it.

[350zavage]

I thought 'cxu' was for only yes or no questions?

[Rae.F]

Think of ĉu as "is it so that...?"

[polynickglot]

I thought the same thing, but you technically could respond with "Yes, the flag is red or blue."

[portu-maskon]

It be using the x system

[WallieMcKi]

Where did the s come from on bluas saying I had a typo when I typed blua?

[Rae.F]

Did you perhaps leave out the verb "estas"? Next time, copy and paste your full answer so we can see what's going on?