1. When we arrived at the murder scene, it had been cordoned off by the police.2. The police cordoned off the scene of the crime so that passers-by could not get close.
cordon offcordon off 指在某個地方拉起布條、繩子等，讓別人知道此地方禁止進入現場拉起了禁止進入的布條 = This area has been cordoned off.< >
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 effect, which leads to melting of glacers, which leads to rising sea levels.