Pair up pairs and write opposite words: butterfly to what? Spring rain to what? Singing pairs of what? Flower to what? Red to what? Thanks for the guidance!

Butterflies to bees or ants or flowers, spring rain to autumn wind, singing to dancing or poetry, flowers to grass

Red can be used for all colors, and red is a flat sound, so it's best if that word is oblique.

For example, red vs. green, red vs. purple, red vs. black are all possible

The above is my personal opinion and some information, thank you!