One needs to watch their associations closely so they don't hang out with bad friends.
 bad friends misfit friends
這是一個連環問題: 燃燒石油導致二氧化碳增加，二氧化碳增加導致溫室效應，溫室效應導致冰層融化、海平面上升。 (請填空)
This is a chain of problems. Burning oil leads to increase in carbon dioxide, which leads to the reenhouse effect, which leads to melting of glaciers, which leads to rising sea levels.