我国城市大气污染严重程度冬、春季重于夏、秋季；北方重于南方；大中城市重于小城镇。全国600多座城市中，大气质量真正符合国家一级标准的只有四五个，不到1％。全国降尘污染严重的城市有包头、焦作、鞍山、大同、唐山、哈尔滨、太原和石家庄。1994年，对88个城市统计表明，二氧化硫超过国家二级标准的城市有48个，二氧化硫污染严重的城市有重庆、贵阳。全国出现酸雨的城市每年都有所增加。1994年，对77个城市的统计表明，81．6％的城市出现酸雨，酸雨污染严重的城市依次为长沙、南充、赣州、怀化、梧州。
以下说法正确的是（）。
A．我国城市大气污染冬、春季重于夏、秋季；南方重于北方；大中城市重于小城镇
B．我国城市中大气质量符合国家一级标准的占1％强
C．我国城市中二氧化硫含量超过国家二级标准的有48个
D．以上说法均不对
参考答案：D
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| There are many different ways of seeing a town for the first time. One of them is to walk around it, guide- book 1 hand. Of course, we may 2 with our guide-books the history and 3 developments of a town and get to know them. 4 then, if we take out time and 5 in a town for a while, we may get to know it better. When we 6 it as a whole, we begin to have some 7 , which even the best guide-books do not answer. Why is the town just 8 this, this shape, this plan, this size? Why do its streets 9 in this particular way, and not in any 10 why? Here even the best guide-book 11 us. One can't find in it the information about how a town has developed to the 12 appearance. It may not describe the original (最初的) 13 of a town. However, one may get some idea of what I 14 look like by walking around the town. One can also imagine 15 the town was first planned and . Then one can learn more about in what direction the town 16 to develop. What is the 17 of studying towns in the way? For me, it is 18 that one gets a greater depth of pleasure by visiting and seeing a town with one's own eyes. A 19 visit to a town may help one better understand why it is attractive 20 just reading about it in a guide-book. | ||||
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