21. Shut up, otherwise, you can't follow the lesson.
→ If you don't Shut up ,  you can't follow the lesson.
22. But for the rain, we would have a good picnic.
→ If i didnt rain , we would have a good picnic.
23. Unless he apologizes to me, I won't talk to him.
→ If he apologizes to me, I will talk to him.
24. She wasn't sick. She couldn't take part in the activity.
→ If she had been sick , she would have taken part in the activity.
25. She doesn't like spicy food, so she doesn't eat any food at the party.
→ If  she liked spicy food,  she would eat any food at the party.