If I had known about the event earlier, I ________________ it.

• 3rd Conditional এর নিয়মানুযায়ী,
- - If clause- এ যদি (had + V₃) হয়, তবে পরবর্তী clause a would/could/might + have + V₃ + extension ব্যবহৃত হয়।
- Conditional sentence এ Had + Sub + V₃ + Extension এভাবে কোন sentence শুরু হলে সেটি Perfect conditional / 3rd conditional হয়।

• তাই নিয়মানুযায়ী, শূন্যস্থানে সঠিক উত্তর হবে - would have attended.

Complete Sentence: If I had known about the event earlier, I would have attended it.