A．The climate in recorded human history has generally remained stable.
B．The climate from about 135,000 to 115,000 years ago was in a extremely cold state.
C．The human race has been lucky to have enjoyed the most favorable period of climate for them to build a socio-economic system.
D．The evidences scientists collected from the ice cores suggest that a civilization can not have arisen in the period from about 135,000 to 115,000.

A．We have been changing the climate with thoughtless actions for decades.
B．We have been handling machines with poor skills for decades.
C．We have been following a misleading chapter about the earth for decades.
D．We have been mistaken in the belief in developing the agricultural infrastructure.