Supergrass
n. <英>向警方提供大量罪犯活动情报的人（尤指本人也是罪犯的人）
🗣️ 情景例句
It's midnight.
都午夜了。
You've done me a great favour.
您帮了我大忙。
During a holiday in Sweden, I found this note on my car: 'sir, we welcome you to our city.
“先生，欢迎您光临我们的城市。