Understanding Voice Change: Passive to Active

The question asks us to convert a sentence from its passive form into its active form. The original sentence is: By whom has this mischief been done?

Let's break down the sentence and the process of converting it to the active voice.

Analyzing the Passive Sentence

• The sentence starts with "By whom", which indicates the agent (the doer of the action) is being asked about.
• "has this mischief been done" is the verb phrase. The structure "has/have + been + past participle" is characteristic of the Present Perfect tense in the passive voice.
• "this mischief" is the subject of the passive sentence, but it is actually the object of the action.

The structure of a passive sentence in the Present Perfect tense is:

\(\text{Object} + \text{has/have} + \text{been} + \text{Past Participle} (+ \text{by Subject})\)

For our sentence (which is a question):

\(\text{By whom} + \text{has} + \text{Subject (this mischief)} + \text{been done}?\)

Converting to Active Voice

To change a passive sentence to active voice, we need to:

1. Identify the agent (the doer of the action). This will become the subject in the active voice. In "By whom has this mischief been done?", the agent is unknown and being asked about, represented by "whom". When converting a question starting with "By whom", the active sentence will start with "Who".
2. Identify the verb and its tense. The passive verb is "has been done", which is Present Perfect Passive. The active verb must be in the same tense, i.e., Present Perfect Active. The active form of "done" is "do", and the Present Perfect Active is "has/have + past participle".
3. Identify the subject of the passive sentence (which is the object in the active voice). In "this mischief", this is the object.
4. Rearrange the sentence into the active structure: Subject + Verb + Object.

The structure of an active sentence in the Present Perfect tense is:

\(\text{Subject} + \text{has/have} + \text{Past Participle} + \text{Object}\)

Applying this to our sentence:

• Subject: "Who" (from "By whom")
• Verb (Present Perfect Active): "has done"
• Object: "this mischief"

Putting it together as a question, we get: Who has done this mischief?

Evaluating the Options

Let's look at the given options:

1. Who has been doing this mischief? - This is in the Present Perfect Continuous active tense. Incorrect tense.
2. Who is doing this mischief? - This is in the Present Continuous active tense. Incorrect tense.
3. Who did this mischief? - This is in the Simple Past active tense. Incorrect tense.
4. Who has done this mischief? - This is in the Present Perfect active tense, matching the original passive tense. The structure is correct for a question starting with "Who".

Comparing our derived active sentence with the options, option 4 matches perfectly.

Therefore, the correct active form of the sentence "By whom has this mischief been done?" is "Who has done this mischief?".

Revision Table: Active vs. Passive Voice Basics

Additional Information: Voice Change Rules for Questions

Changing the voice of interrogative (question) sentences requires special attention. Here are some key points:

• Maintain the question form: The converted sentence must also be a question.
• Questions beginning with 'Who' or 'Whom':
  • If the passive sentence starts with 'By whom', the active sentence starts with 'Who'. (Example: By whom was the glass broken? > Who broke the glass?)
  • If the passive sentence starts with 'Who', the active sentence starts with 'By whom'. (Example: Who is loved by everyone? > By whom is everyone loved?)
  • If the active sentence starts with 'Who' (acting as subject), the passive sentence will start with 'By whom'. (Example: Who wrote this letter? > By whom was this letter written?)
  • If the active sentence starts with 'Whom' (acting as object), the passive sentence will start with 'Who'. (Example: Whom did you see? > Who was seen by you?)
• Questions beginning with other 'Wh' words (What, Where, When, Why): These words usually remain at the beginning in both active and passive forms.
• Questions beginning with helping verbs (Is, Are, Was, Were, Do, Does, Did, Has, Have, Had, Will, Shall, Can, Could, etc.): The helping verb structure needs to be maintained in the converted voice, adjusting the form of 'be' and the main verb accordingly. (Example: Did he write the letter? > Was the letter written by him?)

In our specific question, "By whom has this mischief been done?", the starting word "By whom" correctly converts to "Who" in the active voice question, following the rule for questions about the agent.