Question

La __________ es donde te sientas en el cine o en el teatro.

Answer 1

I agree with the person above - La silla es donde te sientas en el cine o en el teatro.
A chair is where you sit in a cinema or a theater. 

Answer 2

The first thing we are going to do for this case is to translate the incomplete sentence into English.

We have then:

The __________ is where you sit in the cinema or in the theater.

We now choose a word to complete the sentence.

We have then:

Chair

Substituting we have:

The chair is where you sit in the cinema or in the theater.

The translation of the sentence in Spanish is:

La silla es donde te sientas en el cine o en el teatro.

Answer:

Silla

La silla es donde te sientas en el cine o en el teatro.