Fill in the blank in the following sentence with the help of the given options.
We had completed our paper when the bell__________.

Correct option is A

The correct option to fill in the blank is (a) rang.
Explanation: In a past-time sequence, Past Perfect ( had completed) marks the earlier action; the action that occurs after it takes Simple Past ( rang). Hence: “We had completed our paper when the bell rang.”
Example: “They had left the hall when the lights went out.”
नियम: जब भूतकाल में दो घटनाएँ हों और एक घटना दूसरी से पहले पूरी हो चुकी हो, तो पहले वाली घटना के लिए Past Perfect (had + V³) और बाद की घटना के लिए Simple Past (V²) का प्रयोग होता है।
उदाहरण संरचना: Past Perfect + when + Simple Past
Why other options are incorrect:
· (b) had rung would make both clauses past perfect, blurring the sequence marker “when.”
· (c) had been rung (passive past perfect) is unnecessary and stylistically odd here.
· (d) was ringing (past continuous) suggests an ongoing action but the bell typically rings as a punctual event marking the moment.
Booster (rule): Use Past Perfect for the earlier of two past events and Simple Past for the later event introduced by when/after/before as context demands.