夏天省电小妙招是呆在地下室吗？

败家
9

还有radon

A map of geologic radon potential in the United States. The "high" potential includes all of eastern South Dakota and the ridge around the Black Hills. (Courtesy of USGS)
A map of geologic radon potential in the United States. The "high" potential includes all of eastern South Dakota and the ridge around the Black Hills. (Courtesy of USGS)760×586 17.9 KB