The result or effect clause of a conditional sentence sometimes uses a modal auxiliary other than will or would. In Conditionals II and III, could and might can be used as well.
If a storm hits, it might be dangerous.
If it’s 10:00, we must have slept about twelve hours.
If you came to Seoul with me, we could visito Japan as well.
If we weren’t so busy all the time, we could read more.
If I had known you wanted a camera, I could have bought you one in Hong Kong.
If Johnson had played, we might have won.
Using might rather than would or could usually indicates that a possibility is LESS LIKELY.
Negative conditional sentences are common:
If I had realized that you already had one, I wouldn’t have bought another.
She would never have learned the truth if she hadn’t read that letter.
If they hadn’t known him, they would never have helped him.
You wouldn´t have saved all that money if you hadn´t bought the car from me.
If they can´t go tonight, they can go tomorrow instead.
Though if is by far the most common word for introducing conditional clauses, several other terms are used as well:
Unless we solve the problem now, it´s going to last for years.
As long as he doesn´t fall this final test, the university will probably let him stay.