When the Black Death broke out in Europe the world sunk into a huge economic recession, which took years to recover.
An economic recession< >
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 greenhouse effec, which leads to melting of glaciers, which leads to rising sea levels.