Different formulas used in ACTIVE & PASSIVE VOICE
Firstly, Active voice
is the sentences in which the subject
is a doer of an action.
             E.g. Mduwile is looking for
us. 
Now from the sentence above, Mduwile is a doer (subject) of action (looking) in this way the subject can be either
a NOUN or PRONOUN. As we seen mduwile is a Noun.
Passive voice is the sentence where by an object
seems to be a receiver of an action.
              E.g. we are being looked by
Mduwile.
As sentence above, We is a receiver (object)
of an action (looked) also the object can 
be either NOUN or PRONOUN. As we see in the sentence “we” is a pronoun.
Try to pass a little through this table below ready to understand those structures;
| 
   TENSE TYPE  | 
  
   ACTIVE VOICE STRUCTURE  | 
  
   PASSIVE VOICE STRUCTURE  | 
 
| 
   Simple present   | 
  
   Subject + V1+es/s + object  | 
  
   Object + is/are/am + V3 + by + subject  | 
 
| 
   Present continuous   | 
  
   Subject + is/are/am + ...ing verb + object  | 
  
   Object + is/are/am + being + V3 +by +  Subject  | 
 
| 
   Present perfect  | 
  
   Subject + has/have + V3 + object  | 
  
   Object + has/have + been + V3 + by +  subject  | 
 
| 
   Simple past  | 
  
   Subject + V2 + object  | 
  
   Object + was/were + V3 + by + subject  | 
 
| 
   Past continuous  | 
  
   Subject + was/were + ...ing verb + object  | 
  
   Object + was/were + being + V3 + by + subject  | 
 
| 
   Past perfect  | 
  
   Subject + had + V3 + object  | 
  
   Object + had + been + V3 + by + subject  | 
 
| 
   Simple future  | 
  
   Subject + will/shall + V1 + object  | 
  
   Object + will/shall + being + V3 + by +
  subject  | 
 
| 
   Future continuous  | 
  
   Subject + will/shall + being + ...ing verb +
  object  | 
  
   Never change  | 
 
| 
   Future perfect  | 
  
   Subject + will/shall + have + V3 +
  object  | 
  
   Object + will/shall + have + been + V3
  + by + subject  | 
 
Perfect continuous in (Present tense, past tense and future tense) never change.
This means that “present perfect continuous, past perfect continuous and future perfect continuous tense” does not have any formula to change from active into passive voice. Continue to pass through this website for next articles about Active and passive voice.
From the table, what is v1, v2 & v3
V1, is the origin vocabulary (verb). E.g. know
V2, is the verb in past tense. E.g. Knew
V3, is the verb which is in perfect tense. E.g. Known
Welcome
By Mduwile joseph