The first letters sent by Pony Express from California took ten days to reach Missouri.

VOA: special.2009.05.28

We just need the ten letters of Paul that he knew about.

我们只需要保罗的十封书信。

耶鲁公开课 - 新约课程节选

But he seemed to only include ten letters in his list.

他似乎只把十封信列入了他的清单里。

耶鲁公开课 - 新约课程节选