Change the following from active to passive:

📌 Explanation:

Active Sentence:
The agency had been monitoring dissent groups covertly for months.

👉 Tense = Past Perfect Continuous
👉 Structure = Subject + had been + V-ing

🔄 Passive Rule:

👉 Past Perfect Continuous (rare in passive) →
Object + had been being + V³ + by + subject

✔️ Strict form:
Dissent groups had been being monitored… (grammatically correct but awkward)

👉 So, in practical English (and exams), we simplify to:
had been monitored

❌ Why options are wrong:

1. Dissent groups had covertly monitored the agency. ❌
   → Meaning changed (wrong subject-object)

2. had have been monitored… ❌
   → Grammatically incorrect (“had have” wrong)

3. Covert monitoring had occurred… ❌
   → Changes sentence structure (not proper passive)

4. The dissent groups were under surveillance. ❌
   → Not a true passive transformation

💡 Extra Facts (Important for Exams):

1. Rare Passive Forms:

👉 Continuous perfect tenses (like this one) are rarely used in passive

2. Exam Strategy:

👉 If exact passive sounds awkward → use closest correct standard form

✔️ Final Tip:

👉 Always check:

• Same meaning

• Correct tense

• Proper structure