A:Burning rubbish in the open air.
B:Planting trees in spring.
C:Walking or riding bikes to school.
D:Taking a shopping basket when going shopping.
2013年3月19日我国宣布研制出“全碳气凝胶”,其密度是0.16mg/cm3,成为已知的最轻固态材料.对这种物质的认识正确的是( )
根据板块构造学说的观点,因板块相互碰撞挤压而形成的地貌类型是( )