Dan could have won the dance competition if he hadn't broken his leg. Did he break his leg? Did he win the competition?
Yes and No!
What / happen / covid vaccine / not be invented?
What would've happened if the covid vaccine hadn't not be invented?
Jasper didn't wear a coat, and he got a cold.
If Jasper had worn a coat, he wouldn't have caught a cold.
I didn't see the hole and I fell into it.
If I had seen the hole, I wouldn't have fallen into it.
