Writing letters seems to be a thing of the past.

写信好像已是昔日的事情了。

They thought bank runs were a thing of the past.

他们还以为银行挤兑是过去才发生的事儿。

Well, those problems may soon be a thing of the past!

这些问题可能很快就成历史了！

Cheap food, like cheap oil, may be a thing of the past.

便宜的粮食，和便宜的石油，恐怕都是很遥远的往事了。

But this complex system soon will be a thing of the past.

不过，这种复杂的系统不久就会成为历史。