Scientist have dated sharp-edged flakes of stone found in the fine-grained sediments of a dry riverbed in the Afar region of Ethiopia to between 2.52 and 2.60 milion years ago, pushing back by more than 150,000 years the earliest date /when it is known that humans make/ stone tools
when is is known that humans make
at which it is known that human had made
at which humans are known to have made
that humans are known to be makin
of humans who were known to make.
correc A. is C, please, explain, what wrong with A
when is is known that humans make
at which it is known that human had made
at which humans are known to have made
that humans are known to be makin
of humans who were known to make.
correc A. is C, please, explain, what wrong with A
