Ser vs Estar example

[DavidT]

Hello all,

I took an online test with the following question and had to fill in the correct Ser or Estar form.

Esas ventanas  ________ hechas de vidrio.

I put in "son" but the correct answer is "esta'n" and I don't understand why.  I went with "son" due to the window being glass as something permanent and possibly a characteristic...both "son" tendencies.

Any help would be greatly appreciated,

Thanks!

David

[Lorei]

Se dice "están hechas de vidrio". Aquí la palabra clave es "hechas". En una oración tipo: "Esto es madera" se usaría el verbo "ser". Pero las cosas siempre ESTÁN hechas de un material.