Basics on passive voice

1.  Passive Voice
En el siguiente ejemplo la oración esta en voz activa y en pasado simple.
Active Voice:
subject transitive Verb object
Ruben broke the mirror.
En este ejemplo la oración esta en voz pasiva. El [object] pasa a ser el [subject] de la oración
anterior.
Passive Voice:
subject verb [be] + past participle
The mirror was broken by Ruben.
Para poder formar [passive voice] a partir de la [active voice] es necesario tener incluido un
[transitive verb] (verbos a los que les puede seguir un [object]) No se pueden usar [intransitive
verbs] con [passive voice]
Intransitive verb example:
Subject intransitive verb
An accident happened.
Tenses chart
Active Passive
simple present Mary writes a letter. A letter is written by Mary.
present progressive Mary is writing a letter. A letter is being written by Mary.
present perfect* Mary has written a letter. A letter had been written by Mary.
simple past Mary wrote a letter. A letter was written by Mary.
past progressive Mary was writing a letter. A letter was being written by Mary.
past perfect* Mary had written a letter. A letter had been written by Mary.
simple future* Mary will write a letter. A letter will be written by Mary.
be going to Mary is going to write a letter. A letter is going to be written by Mary.
future perfect* Mary will have written a letter. A letter will have been written by Mary.
*Estos tiempos son rara vez usados en su forma [passive]