Over80percentofmankind’sdietisprovidedbytheseedsofles...
问题详情： Over80percentofmankind’sdietisprovidedbytheseedsoflessthanadozenplantspecies.Buttheamountandvarietyofcropproductionhasbeenincreasingallthetime. ____56____Forexample,Egyptianssettledalo...