"Neden havuzda yok?"

Translation: Why is she not in the pool?

[jswartzentruber]

Could you also express this by saying "Neden havuzda degil"?

[TechnicalUK]

Couldn't that be interpreted as "Why not at the pool?" With no he/she/it?

[A1fie]

"yok" and "değil" take some time to master. They are used interchangeably in many contexts, but not always.

yok = there isn't (something)

değil = it is not (there)

She is not home = O evde değil ~ O evde yok.

There is no bread at home = Evde ekmek yok. (Evde ekmek değil is simply WRONG)

I guess you just need to memorize as many examples as possible to get it eventually.

[KanbakCan]

I do not think this is a correct sentence. Yok is not a proper verb in Turkish and this sentence does not have any verbs.

[TechnicalUK]

I may be incorrect but I take it that the yok is the way you know you are talking about someone or something being there or not? - Why at the pool does not exist? (no suffix for havuz indicates the use of he/she/it.) Just my understanding anyway.