worst cold case

例句：

1. 1. The worst cold case in history has never been solved.
   历史上最冷的案件从未被解决。
2. 2. This is the coldest case we've ever encountered.
   这是我们遇到过的最冷的案件。
3. 3.The cold case investigation is still ongoing.
   这个冷案调查仍在进行中。