How much were the CO2 levels before the Industrial Revolution?A.400 parts per million.B.28
专四
已帮助 人
How much were the CO2 levels before the Industrial Revolution?
A.400 parts per million.
B.280 parts per million.
C.120 parts per million.
D.680 parts per million.
请帮忙给出正确答案和分析,谢谢!
