If I _________ him, I would have told him the news.

Correct answer: had seen.
Complete sentence: If I had seen him, I would have told him the news.
- প্রদত্ত বাক্যটি 3rd conditional এর উদাহরণ। পরবর্তী Clause এ would not have এর পর verb এর past participle হওয়ায় "If" যুক্ত Clause টি past perfect tense হবে।

• Third conditional-এর নিয়মানুযায়ী:
- If clause (শর্তযুক্ত অংশে)-এ যদি (had + V3) হয়, তবে পরবর্তী clause -এ would/could/might + have + V3 + extension হয়।
- Structure: If + Past Perfect (had +V3) + Subject + would/could/might + have + verb-এর past participle.
- Negative অর্থ প্রকাশ করলে would/could/might + not হয়।

Source:
1. A Passage to the English Language by S.M. Zakir Hussain.
2. Website English Wizard by Saleh Ahmed.