Tag questions, pasive voice and active voice

INDICE
PASSIVE VOICE______________________________________________3
ACTIVE VOICE_______________________________________________9
ACTIVE-PASSIVE VOICE______________________________________11
COMPARATIVES____________________________________________13
SUPERLATIVES_____________________________________________18
COMPARATIVESSUPERLATIVES_______________________________22POSPRETERITO____________________________________________25
COPRETERITO_____________________________________________27
BIBLIOGRAPHY_____________________________________________30

PASSIVE VOICE
In passive sentences, the thing receiving the action is the subject of the sentence and the thing doing the action is optionally included near the end of the sentence. You can use the passive form if you think that thething receiving the action is more important or should be emphasized. You can also use the passive form if you do not know who is doing the action or if you do not want to mention who is doing the action.
[Thing receiving action] + [be] + [past participle of verb] + [by] + [thing doing action]
Examples:

We use the passive form to say what happens to people and things, to say what is done tothem. For example:
* English is spoken here.
* The car is being repaired.
We use the passive form when we don't know who did the action. For example:
* The car was damaged while it was parked on the street.
* The shirts were made in Turkey.
We use the passive form when what was done is more important than who did it. For example:
* It was approved by Gerry last week.
* I wasinformed by the Human Resources Manager only two days ago.
Use of Passive
Passive voice is used when the focus is on the action. It is not important or not known, however, who or what is performing the action.
Example: My bike was stolen.
In the example above, the focus is on the fact that my bike was stolen. I do not know, however, who did it.
Sometimes a statement in passive is more politethan active voice, as the following example shows:
Example: A mistake was made.
In this case, I focus on the fact that a mistake was made, but I do not blame anyone (e.g. You have made a mistake.).
Form of Passive
Subject + finite form of to be + Past Participle (3rd column of irregular verbs)
Example: A letter was written.
When rewriting active sentences in passive voice, note thefollowing:
* the object of the active sentence becomes the subject of the passive sentence
* the finite form of the verb is changed (to be + past participle)
* the subject of the active sentence becomes the object of the passive sentence (or is dropped)
Examples of Passive
Tense | Subject | Verb | Object |
Simple Present | Active: | Rita | Writes | a letter. |
| Passive: | A letter |is written | by Rita. |
Simple Past | Active: | Rita | Wrote | a letter. |
| Passive: | A letter | was written | by Rita. |
Present Perfect | Active: | Rita | has written | a letter. |
| Passive: | A letter | has been written | by Rita. |
Future I | Active: | Rita | will write | a letter. |
| Passive: | A letter | will be written | by Rita. |
Hilfsverben | Active: | Rita | canwrite | a letter. |
| Passive: | A letter | can be written | by Rita. |
Examples of Passive
Tense | Subject | Verb | Object |
Present Progressive | Active: | Rita | is writing | a letter. |
| Passive: | A letter | is being written | by Rita. |
Past Progressive | Active: | Rita | was writing | a letter. |
| Passive: | A letter | was being written | by Rita. |
Past Perfect | Active: |Rita | had written | a letter. |
| Passive: | A letter | had been written | by Rita. |
Future II | Active: | Rita | will have written | a letter. |
| Passive: | A letter | will have been written | by Rita. |
Conditional I | Active: | Rita | would write | a letter. |
| Passive: | A letter | would be written | by Rita. |
Conditional II | Active: | Rita | would have written | a...