Answer:
I found a source where it says that the sentences should be transformed from object nouns into direct object pronouns.
Step-by-step explanation:
1. No tengo la llave de la habitación
I don't have the key to the bedroom.
No la tengo. (what? ) --> la llave
I don't have them.
2. El botones pone el equipaje en el taxi.
The bellboy puts the luggage in the taxi.
El botones lo pone. (what?) --> el equipaje.
The bellboy puts it.
3. Juanita toma fotos en la playa.
Juanita takes pictures on the beach.
Juanita las toma. (what?) ---> las fotos.
Juanita takes them.
4. Mi tío compra un boleto para el partido de fútbol.
My uncle buys a ticket for a football match.
Mi tío lo compra. (what?) --> un boleto.
My uncle buys it.
5. Mis hermanas y yo buscamos a nuestros padres.
My sisters and I are looking for our parents.
Mis hermanas y yo los buscamos. (who?) --> nuestros padres.
My sisters and I are looking for them.
6. Inés y Luisa quieren ver los monumentos.
Inés and Luisa want to see the monuments.
Inés y Luisa los quieren ver. (what?) --> los monumentos.
Inés and Luisa want to see them.
7. Estamos explorando el centro de la ciudad.
We are exploring the city center.
Le estamos explorando. (what?) --> el centro
We are exploring it.
8. Laura está escribiendo unas postales.
Laura is writing some postcards.
Laura las está escribiendo. ( what? ) --> las postales
Laura is writing them.