The United States built a national highway system to expand transportation.

VOA: special.2010.03.19

So even if we had a transportation system as nice as San Francisco,

所以即使我们有旧金山那样好的交通系统，

大众交通枢纽 - SpeakingMax英语口语达人

You have to have a good public transportation system when you have as many people here as we do.

如果你那儿和我们这儿的人一样多，你们得有一个良好的公共交通系统。

纽约的交通手段 - SpeakingMax英语口语达人