I'm sure that they must have visited the place before帮忙翻译下.

问题描述:

I'm sure that they must have visited the place before帮忙翻译下.

我确定他们以前就曾经来着旅游过/拜访过。

我确定他们以前一定来参观过这里。

我肯定他们以前绝对去过那个地方。

我确定他们以前肯定来过这个地方

我能确信,他们以前一定来过这个地方.