"Are these your glasses?"
Translation:Це твої окуляри?
Oh no. Ці is these indeed, but only when it determines the noun itself. In this context, however, it's just like "is it your glasses?". When you can put "it" instead of "this/that/these/those", you use neutral це: Це мої окуляри — these are my glasses (== it is my glasses); Ці окуляри — мої — these glasses are mine.