ACTIVE AND PASSIVE VOICE

Voz Activa The lady buys a new hat. La dama compra un sombrero nuevo. (El verbo "comprar" recae sobre "la dama" indicando que ella es quien realiza la acción)

Voz Pasiva A new hat is bought by the lady. Un nuevo sombrero es comprado por la dama. (En este caso interesa que "un nuevo sombrero es comprado" sin demasiada importancia de quien realiza la acción)

Para construir la voz pasiva es necesario que la oración en voz activa cuente con objeto directo, es decir que responda a la pregunta "¿qué cosa?", por ejemplo:

My sister lost the keys. Mi hermana perdió las llaves. ¿Qué cosa perdió mi hermana? Las llaves (éste es el objeto directo)

Luego el objeto directo establecido pasará a ocupar el lugar de sujeto, el sujeto de la voz activa pasa a ser complemento agente acompañado de la preposición BY y el verbo principal se coloca en pasado participio acompañado por el verbo TO BE en el tiempo que se encuentra la voz activa. Por ejemplo:

My sister lost the keys. The keys were lost by my sister.

Observe en la oración pasiva que "the keys" ocupan el lugar de sujeto, "by my sister" es el complemento agente y el verbo principal está ahora en pasado participio acompañado por el verbo to be (were) en pasado simple ya que la oración activa se encontraba en ese tiempo verbal.

Veremos en el siguiente cuadro como se modifican los verbos de Voz Activa a Voz Pasiva:

Tiempo Verbal de la oración en voz activa	VOZ ACTIVA	VOZ PASIVA
Presente Simple	My brother studies the lesson.	The lesson is studied by my brother.
Presente Continuo	My brother is studying the lesson.	The lesson is being studied by my brother.
Pasado Simple	My brother studied the lesson.	The lesson was studied by my brother.
Pasado Continuo	My brother was studying the lesson.	The lesson was being studied by my brother.
Futuro Simple	My brother will study the lesson.	The lesson will be studied by my brother.
Futuro Cercano	My brother is going to study the lesson.	The lesson is going to be studied by my brother.
Presente Perfecto	My brother has studied the lesson.	The lesson has been studied by my brother.
Pasado Perfecto	My brother had studied the lesson.	The lesson had been studied by my brother.

Pasa las siguientes frases activas teniendo en cuenta de utilizar correctamente los tiempos verbales:

Tommy will know Machu Picchu ruins in Peru. My boss sent me detailed instructions. Sam's friend solved the problem. The workers will complete the new road in the next year. Paul is going to repair the car. My brother forgot his wallet at the bank. My sister will sent a letter to my mother. The little girl is drawing her pet. She dropped her bag in the train. My brother takes his medicine every day. John and Fred will climb the Aconcagua Mountain. My wife crashed the new car. I opened the windows. I drink a glass of water. You did not send the parcel. They did not catch the thieves. Jane has taken some photographs. The passengers are going to visit the museum. The teacher made a big mistake. Mary was preparing a lot of food