Answer:
1. The boy laughed, so the girl giggled.
2. The brown squirrel ran up the tree, and the dog did not bark.
3. Julie wanted a piece of cake, but her mom said no.
4. It was bedtime, yet it was still daylight.
Explanation:
To create a compound sentence, simply use a comma and a coordinating conjunction (and, but, yet, so, or, for, nor).
