Choose the correct passive construction of the given sentence.
Why did your friend write such a letter?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Why was such a letter written by your friend?
Active to passive voice (Wh-question, simple past):
| Change | Active | Passive | Why |
|---|---|---|---|
| Object becomes subject | such a letter | such a letter (subject) | The object “such a letter” becomes the subject of the passive sentence. |
| Tense kept | did ... write | was written | Be + past participle in the same tense. The active verb “did ... write” is simple past, so it becomes “was written” (“was” because “a letter” is singular). |
| Agent (by ...) | your friend | by your friend | The doer “your friend” goes after the verb as “by your friend”. |
| Question form | Why did ... | Why was ... | “Why” stays first and the helping verb “was” comes before the subject. |
| Full sentence | Why did your friend write such a letter? | Why was such a letter written by your friend? |
Example: Who wrote this poem? → By whom was this poem written?
Why the Other Options are Incorrect?
Option 1: Why does your friend write such a letter? — Incorrect.
- It is still in the active voice.
- It changes the simple past into the simple present ("does ... write").
Option 2: Why is such a letter written by your friend? — Incorrect. It is passive, but "is written" is the simple present. The active sentence is in the simple past, which needs "was written".
Option 3: Why will your friend write such a letter? — Incorrect.
- It is still in the active voice.
- It changes the simple past into the simple future ("will write").
Contrast: in the simple past, "did + verb" in the active becomes "was/were + past participle" in the passive.