Had you been careful, the incident ________ happened.

Complete sentence: Had you been careful, the incident would not have happened.
- প্রদত্ত বাক্যটি 3rd Condition এর উদাহরণ।
- 3rd Condition এর নিয়মানুযায়ী ১ম clause এ had + Verb এর past participle form থাকলে পরবর্তী clause would have + Past Perfect হবে।

Third Conditional এর নিয়ম:
- Structure: If + Past Perfect (had +V3) + Subject + would/could/might + have + verb-এর past participle.
- Negative অর্থ প্রকাশ করলে would/could/might + not হয়।
- Conditional sentence এ Had + Sub + V3 + Extension এভাবে কোন sentence শুরু হলে সেটি Perfect conditional / 3rd conditional হয়।
- If clause- এ যদি (had + V3) হয়, তবে পরবর্তী clause a would/could/might + have + V3 + extension ব্যবহৃত হয়।
- অতএব, নিয়মানুযায়ী would not have happened উত্তর হবে।

Source: Advanced Learner's Communicative English Grammar and Composition by Chowdhury and Hossain.