關於Canaries的意思和用法的提問

A: "Canary in a coal mine" is an idiom. It refers to someone or something that will alert others to danger, if it's present. A "canary" does not always refer to a bird. In some cases, as in "warrant canaries," they can be as simple as pieces of paper, or a webpage.

Coal miners used to take canaries into the mines. If the canary died, that alerted the miners to the presence of dangerous methane gas.

"They were canaries in the most dangerous mineshaft ever" means that the birds were able to warn of danger in a situation that is already incredibly fragile and dangerous.

A: Yes, canaries were used in early mines (coal specifically), before they had modern ventilation systems, because they were very sensitive to methane and carbon monoxide. If too much of either gas built up in the mine, the bird would die (and stop singing), signaling to the miners that it was unsafe and they should evacuate.