The central idea is what the main thing. For this, I think the central idea is simply Cactuses.
I'm not sure what another supporting detail can be, but if there's a back side, or another page about cactuses, I can sure help! But if that's the only side, ask your parents. xD
I think wonderful things is about some very nice things in the world. We need to conserve these things because of global warming and climate change so if humans don't change these things will be ruined.
