No sooner had I opened the book than the lights ____ out.

Complete sentence: No sooner had I opened the book than the lights went out.

• No sooner had.....than হচ্ছে Correlative conjunction.
- No sooner had.....than যুক্ত বাক্য গঠনের নিয়মাবলী:
- No sooner had + subject + 1st clause (verb এর past participle) + than + subject + 2nd clause (verb এর past form).

• No sooner had, Hardly had, Scarcely had সবগুলোই "করতে না করতেই/ হতে না হতেই" এ রকম অর্থে ব্যবহৃত হয়

• নিয়মানুযায়ী,
- No sooner had থাকলে পরের অংশে than (then নয়) ব্যবহৃত হয়।
- Hardly had থাকলে পরের অংশে when ব্যবহৃত হয়।
- Scarcely had থাকলে পরের অংশে when (than নয়) ব্যবহৃত হয়।

More Example:
1. No sooner had I opened the book than the lights went out.
2. No sooner had the teacher begun the lesson than the fire alarm rang.