And while these two cities have the same population, San Diego has grown six times larger than Tijuana in the last decades, immediately thrusting us to confront between sprawl and density, which are at the center of today's discussion about environmental sustainability.
这两个城市有一样的人口数量， 但是在过去的10年里面，圣地亚哥扩张了 近六个蒂华纳的面积。 这就使得我们要立即面对 由于城市扩张和密度增加带来的 紧张和冲突， 也就是我们今天要讨论的 关于环境可持续性的重要内容。