No sooner had I entered the classroom _________.

Complete sentence: No sooner had I entered the classroom than the lecture began.

• 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 he finished his breakfast than the phone rang.
2. No sooner had she stepped outside than it started raining.
3. No sooner had we sat down for dinner than the phone rang.