This is what I want to talk about today, and I want to start by defining some terms and then I want to describe the scale of the problem I think we face and then suggest the ways that I believe cities can be the seat of the solution.
这就是今天我想跟大家谈论的主题。 我想从解释一些概念开始， 然后我会阐述我们目前 面临的问题， 进而给出解决办法，即城市是 解决问题的根本。