And that was only possible because, besides using the sea, the shipping lanes for travel, which was much faster than overland travel, the Romans maintained roads.

之所以能达到这个数字，原因之一是走海路，用海洋航路运输，比陆路快得多，另一个原因就是修路。

耶鲁公开课 - 新约课程节选

As carefully as people work with radioactivity here, and using often much, much safer radioactive materials than radium bromide, and using them, and special hoods, and having special procedures, they still do a lot of checking with these Geiger counters to make sure everything's safe.

虽然在这里人们,用放射性物质都非常的小心，而且通常用的材料放射性,都比溴化镭要小得多，并且用的时候,都用特殊的容器,特殊的操作过程,但我们平时仍会用。

麻省理工公开课 - 化学原理课程节选