Active Voice : - In the active voice, the sentence's subject performs the action on the action's target.

Passive Voice : - In the passive voice, the target of the action is the main focus, and the verb acts upon the subject.

Conversion  of Passive Voice Sentence into Active Voice For Perfect Tense:

Past perfect tense:

Rule used to identify that the sentence is in Passive Form with Past Perfect Tense is:

 :subject + had + been + third form of verb + by + object.

For Example:

• Your mind had been changed by you. ( passive )

The subject is 'Your mind' ,object is 'you' and 'changed' is the third form of the verb change.'been' and 'by' is used according to the rule.

While converting into Active Voice the rule will be :

 subject + had + third form of verb + object.

In the question : -

1. An important lesson had been learnt by me.

The active form of above sentence for past  perfect tense :

I had learnt an important lesson. In this sentence , object ( An important lesson ) is converted into subject ( I ) , then use helping verb had because I is a singular subject , then use third form of verb learnt and then object( An important lesson ) .

2. A big mistake had been made by Amar .

Amar had made a big mistake. In this sentence , object ( A big mistake) is converted into subject ( amar ) , then use helping verb had because I is a singular subject , then use third form of verb made and then object( A big mistake ) .

Thus , the Correct Option is D ,  which is 1. I had learnt an important lesson. 2. Amar had made a big mistake.

Active Voice : - In the active voice, the sentence's subject performs the action on the action's target.

Passive Voice : - In the passive voice, the target of the action is the main focus, and the verb acts upon the subject.

Conversion  of Passive Voice Sentence into Active Voice For Perfect Tense:

Present Perfect Tense:

Rule used to identify that the sentence is in Passive Form with Present Perfect Tense is:

     subject + has/have + been + third form of verb + by + object

For Example:

• Furniture has been made by the carpenters.( passive )

The subject is 'furniture' ,object is 'the carpenters' and 'made' is the third form of the verb make.'been' and 'by' is used according to the rule.

While converting into Active Voice the rule will be :

 subject + has/have + third form of verb + object.

In the question : -

This has never been done before by anyone.

The active form of above sentence for perfect tense :

Nobody has done this before. In this sentence , object ( this ) is converted into subject ( nobody ) , then use helping verb has because nobody is a singular subject , then use third form of verb done and then object ( this ) . In objective part under passive voice  , nobody gets changed into anybody .

Thus , the Correct Option is C ,  which is Nobody has done this before.

Active Voice : - In the active voice, the sentence's subject performs the action on the action's target.

Passive Voice : - In the passive voice, the target of the action is the main focus, and the verb acts upon the subject.

Conversion  of Passive Voice Sentence into Active Voice For Perfect Tense:

Present Perfect Tense:

Rule used to identify that the sentence is in Passive Form with Present Perfect Tense is:

     subject + has/have + been + third form of verb + by + object

For Example:

• Furniture has been made by the carpenters.( passive )

The subject is 'furniture' ,object is 'the carpenters' and 'made' is the third form of the verb make.'been' and 'by' is used according to the rule.

While converting into Active Voice the rule will be :

 subject + has/have + third form of verb + object.

In the question : -

1. A lot of people have been helped by my father.

The active form of above sentence for perfect tense :

My father has helped a lot of people. In this sentence , object ( A lot of people ) is converted into subject ( my father) , then use helping verb had ,  then use third form of verb helped and then object( A lot of people ) .

2. A car has been bought recently by Mangesh.

The active form of above sentence for perfect tense :

Mangesh has bought a car recently. In this sentence , object ( A car ) is converted into subject ( mangesh) , then use helping verb had ,  then use third form of verb bought and then object( A car ) .

Thus , the Correct Option is A ,  which is  1. My father has helped a lot of people. 2. Mangesh has bought a car recently .