Fill in the gap: If they ______ earlier, they would have arrived on time.

• Perfect conditional/ 3rd conditional:
- ১ম অংশে Had + sub + V3 এবং পরের অংশে sub + would have/could have/might have + V3 + extension.
Example:
1. If they had left earlier, they would have arrived on time.
2. If he had stayed in the same room as Dave, it would have been a disaster.

Source: Cambridge Dictionary Grammar.