Left, had trekked, has visted, couldn't, bigger
Answer:the correct verb is appears, the subjects are pigeons and building or science building
Explanation:Why I chose appears is because it makes more sense I don’t really know how to explain it. Why didn’t say several large pigeons together is because several large aren’t really subjects, they’re more like adjectives;describing. I don’t really know about the science building because well it might not be a subject because the pigeons are the main ones and I don’t know if it’s science building or just building because science basically tells what the building is. Hope that helps you.
