李天威说，新标准关于PM2.5年均浓度的限值，可以说在国际上处于居中水平。“标准限值之所以不一次收得更严，一方面要坚持以人为本的初心使命，另一方面是立足我国的发展阶段、产业布局、空间结构、资源禀赋、环境容量等基本国情，充分考虑我国的制造业大国地位，以煤为主的能源结构，以重化工为主的产业结构，以公路运输为主的交通运输结构等。
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I genuinely believe making games without a big "do everything" engine can be easier, more fun, and often less overhead. I am not making a "do everything" game and I do not need 90% of the features these engines provide. I am very particular about how my games feel and look, and how I interact with my tools. I often find the default feature implementations in large engines like Unity so lacking I end up writing my own anyway. Eventually, my projects end up being mostly my own tools and systems, and the engine becomes just a vehicle for a nice UI and some rendering...