过几天英语中可以说成 "in a few days" 或 "in several days."

来源：这两个表达都是直接从中文翻译过来的，"in a few days" 来自于中文的 "在几天内"，而 "in several days" 则来自于中文的 "在几天后."

下面是一些例句：

I'll be back in a few days. (我将在几天内回来.)

We will have the meeting in several days. (我们将在几天后开会.)

He will come back in a few days. (他将在几天内回来.)

We will finish the project in several days. (我们将在几天后完成这个项目.)