1. It is common knowledge that smoking is considered one of the nation's leading causes of preventable death, but it's less widely known that cigarettes are also the leading cause of fatal fires.2. It is common knowledge that one plus two equals three.
common knowledgecommon knowledge = 常識
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.