If I had a pen , I (write) a letter, Here the right form of verb is-
- writing
- would write
- will wrote
- had written
Answer: would write
Explanation: Third conditional বাক্যের Structure হলো: If + subject + had + verb এর Past participle রূপ , subject + would/could/might + have + verb এর Past participle রূপ + অবশিষ্ট।