音が流れない場合、再生を一時停止してもう一度再生してみて下さい。
ツール 
画像
MinuteEarth
176188回再生
Why Does Cement Spew So Much CO2?

Cement is responsible for 8% of humanity’s carbon dioxide emissions, which is a problem if we want to build more cities. To reduce the carbon dioxide emitted by the production of cement, people are trying to replace limestone with other types of materials.

コメント