Rocks and Minerals 1. The age of the Earth- The Earth is about 4.6 billion years old. 2. How the layers cooled- As the Earth cooled the heaviest and densest materials sank to the center, and the lightest materials rose to the top. The heaviest materials are the metals i ...
advection 平流 air quality monitoring network 空氣質素監察網 air pressure 氣壓 albedo 反射率 air composition 空氣成分；空氣組成 air mass 氣團 air pollutant 空氣污染物 air pollution 空氣污染；大氣污染 air pollution source 空氣污 ...
Aging population A country that has more than 7% elderly persons (generally referring to people who are more than 65 years old) in its population, is said to have an aging population （老龄化 ） . Examples of countries with aging population are France , Australia and J ...
|Archiver|小黑屋|星韵百科|星韵地理网
( 苏ICP备16002021号 )
动态
日志
相册
分享
微博