Choose the answer that best completes the sentence. yo en la casa.
estamos
estoy
están
estáis
choose the answer that best completes the sentence. las mesas en la sala familiar.
están
está
estamos
estoy
choose the answer that best completes the sentence. la mesa en la sala.
está
estamos
están
estoy
choose the answer that best completes the sentence. las lámparas en el comedor.
estoy
estamos
están
está

We use the verb estar to indicate temporary states and locations. In this way, this verb stands for position, location, action, condition, and emotion. So estoy is the conjugation of the verb estar that matches the first person singular in the simple present tense. The simple present tense is used to talk about habitual actions or routines.  Here the verb estar is being used as location, describing where I'm temporarily. Finally:

Yo estoy en la casa.

Están is the conjugation of the verb estar for the third person plural in the simple present. So las mesas is given in plural form where las is the definite article that matches the feminine plural form and mesas is a feminine plural noun. That's why we choose están. Finally:

Las mesas están en la sala familiar.

Está is the conjugation of the verb estar for the third person singular in the simple present. So la mesa is given in singular form where la is the definite article that matches the feminine singular form and mesa is a feminine singular noun. That's why we choose está. Finally:

La mesa está en la sala.

As in exercise 2, we also choose están here because las lámparas is given in plural form where las is the definite article that matches the feminine plural form and lámparas is a feminine plural noun. That's why we have chosen están. Finally:

Las lámparas están en el comedor.