Sentences can be active or passive. Therefore, tenses also have "active forms" and "passive forms.

" You must learn to recognize

Active Form

In active sentences, the thing doing the action is the subject of the sentence and the thing receiving the action is the object. Most
sentences are active.

[Thing doing action] + [verb] + [thing receiving action]

Examples:

Passive Form

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 the thing 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:
Active / Passive Overview

Tense Active Passive

Simple Present Once a week, Tom cleans the house. Once a week, the house is cleaned by Tom.

Present Right now, Sarah is writing the letter. Right now, the letter is being written by Sarah.
Continuous

Simple Past Sam repaired the car. The car was repaired by Sam.

The salesman was helping the customer when the thief The customer was being helped by the salesman when the
Past Continuous
came into the store. thief came into the store.

Present Perfect Many tourists have visited that castle. That castle has been visited by many tourists.

Present Perfect Recently, John has been doing the work. Recently, the work has been being done by John.
Continuous

George had repaired many cars before he received his Many cars had been repaired by George before he received
Past Perfect
mechanic's license. his mechanic's license.

Past Perfect Chef Jones had been preparing the restaurant's The restaurant's fantastic dinners had been being
Continuous fantastic dinners for two years before he moved to Paris. prepared by Chef Jones for two years before he moved to
 Paris.

Simple Future Someone will finish the work by 5:00 PM. The work will be finished by 5:00 PM.
will

Simple Future Sally is going to make a beautiful dinner tonight. A beautiful dinner is going to be made by Sally tonight.
be going to

Future At 8:00 PM tonight, John will be washing the dishes. At 8:00 PM tonight, the dishes will be being washed by
Continuous John.
will

Future At 8:00 PM tonight, John is going to be washing the At 8:00 PM tonight, the dishes are going to be being
Continuous dishes. washed by John.
be going to

Future Perfect They will have completed the project before the The project will have been completed before the deadline.
will deadline.

Future Perfect They are going to have completed the project before The project is going to have been completed before the
be going to the deadline. deadline.

Future Perfect The famous artist will have been painting the mural for The mural will have been being painted by the famous
Continuous over six months by the time it is finished. artist for over six months by the time it is finished.
will

Future Perfect The famous artist is going to have been painting the The mural is going to have been being painted by the
Continuous mural for over six months by the time it is finished. famous artist for over six months by the time it is finished.
be going to

Used to Jerry used to pay the bills. The bills used to be paid by Jerry.

Would Always My mother would always make the pies. The pies would always be made by my mother.
Future in the Past I knew John would finish the work by 5:00 PM. I knew the work would be finished by 5:00 PM.
Would

Future in the Past I thought Sally was going to make a beautiful dinner I thought a beautiful dinner was going to be made by Sally
Was Going to tonight. tonight.
Sentences in Active and Passive Voice
Here are examples of sentences written in both the active voice and the passive voice, with the active voice sentence appearing first:
Harry ate six shrimp at dinner. (active)
At dinner, six shrimp were eaten by Harry. (passive)
Beautiful giraffes roam the savannah. (active)
The savannah is roamed by beautiful giraffes. (passive)
Sue changed the flat tire. (active)
The flat tire was changed by Sue. (passive)
We are going to watch a movie tonight. (active)
A movie is going to be watched by us tonight. (passive)
I ran the obstacle course in record time. (active)
The obstacle course was run by me in record time. (passive)
The crew paved the entire stretch of highway. (active)
The entire stretch of highway was paved by the crew. (passive)
Mom read the novel in one day. (active)
The novel was read by Mom in one day. (passive)
The critic wrote a scathing review. (active)
A scathing review was written by the critic. (passive)
I will clean the house every Saturday. (active)
The house will be cleaned by me every Saturday. (passive)
The staff is required to watch a safety video every year. (active)
A safety video will be watched by the staff every year. (passive)
She faxed her application for a new job. (active)
The application for a new job was faxed by her. (passive)
Tom painted the entire house. (active)
The entire house was painted by Tom. (passive)
The teacher always answers the students’ questions. (active)
The students’ questions are always answered by the teacher. (passive)
The choir really enjoys that piece. (active)
That piece is really enjoyed by the choir. (passive)
Who taught you to ski? (active)
By whom were you taught to ski? (passive)
The forest fire destroyed the whole suburb. (active)
The whole suburb was destroyed by the forest fire. (passive)
The two kings are signing the treaty. (active)
The treaty is being signed by the two kings. (passive)
The cleaning crew vacuums and dusts the office every night. (active)
Every night the office is vacuumed and dusted by the cleaning crew. (passive)
Larry generously donated money to the homeless shelter. (active)
Money was generously donated to the homeless shelter by Larry. (passive)
No one responded to my sales ad. (active)
My sales ad was not responded to by anyone. (passive)
 
The wedding planner is making all the reservations. (active)
All the reservations will be made by the wedding planner. (passive)
Susan will bake two dozen cupcakes for the bake sale. (active)
For the bake sale, two dozen cookies will be baked by Susan. (passive)
The science class viewed the comet. (active)
The comet was viewed by the science class. (passive)
Who ate the last cookie? (active)
The last cookie was eaten by whom? (passive)
Alex posted the video on Facebook. (active)
The video was posted on Facebook by Alex. (passive)
The director will give you instructions. (active)
Instructions will be given to you by the director. (passive)
Thousands of tourists view the Grand Canyon every year. (active)
The Grand Canyon is viewed by thousands of tourists every year. (passive)
The homeowners remodeled the house to help it sell. (active)
The house was remodeled by the homeowners to help it sell. (passive)
The team will celebrate their victory tomorrow. (active)
The victory will be celebrated by the team tomorrow. (passive)
The saltwater eventually corroded the metal beams. (active)
The metal beams were eventually corroded by the saltwater. (passive)
The kangaroo carried her baby in her pouch. (active)
The baby was carried by the kangaroo in her pouch. (passive)
Some people raise sugar cane in Hawaii. (active)
Sugar cane is raised by some people in Hawaii. (passive)
These different sentences written in both active voice and passive voice illustrate the differences.

Read more at http://examples.yourdictionary.com/examples-of-active-and-passive-voice.html#pscBvfqWFO5PW3fY.99