Voice
English has two voices for verbs: the active and the passive. The basic form is the active verb, and follows the SVO pattern discussed above. The passive voice is derived from the active by using the auxiliary verb "to be" and the past participle form of the main verb.

Examples of the passive:
Passive voice Active voice
I am seen by John John sees me
You will be struck by John John will strike you
It was stolen by John John stole it
We were carried by John John carried us
They have been chosen by John John has chosen them

Furthermore, the agent and patient switch grammatical roles between active and passive voices so that in passive the patient is the subject, and the agent is noted in an optional prepositional phrase using by, for example:

1. active: I heard the music.
2. passive: The music was heard (by me). (Note: me, not I)

The passive form of the verb is formed by replacing the verb with to be in the same tense and aspect, and appending the past participle of the original verb. Thus:
Tense Active voice The same sense, expressed with the passive voice
Simple present I hear the music. The music is heard by me.
Present progressive I am hearing the music. The music is being heard by me.
Past progressive I was hearing the music. The music was being heard by me.
Past perfect I had heard the music. The music had been heard by me.
Simple future I will hear the music. The music will be heard by me.

This pattern continues through all the composite tenses as well. The semantic effect of the change from active to passive is the depersonalization of an action. It is also occasionally used to topicalize the direct object of a sentence, or when the agent is either unknown or unimportant even when included, thus:

1. The plane was shot down.
2. Dozens were killed.
3. Bill was run over by a bus.

Many writing style guides including Strunk and White recommend minimizing use of the passive voice in English; however, many others do not.

There is a third 'voice' in English, related to the classic "middle" voice. In this, the patient becomes the subject, as in passive, but the verb remains in apparently active voice, no agent can plausibly be supplied, and generally an adverbial modifies the entire construction. Thus:

1. She doesn't frighten easily.
2. This bread slices poorly.
3. His novels sell well.
4. Campbell's - the soup that eats like a meal (TM).