Nextautumn,whenyouseegeeseheadingsouthforthewinter,fl...
06-09
問題詳情: Nextautumn,whenyouseegeeseheadingsouthforthewinter,flyingalongin'V'formation,youmightconsiderwhatsciencehasdiscoveredastowhytheyflythatway. 41 eachbirdflapsitswings,itcreatesupliftfo...