Nextautumnwhenyouseewildgeeseheadingsouthforthewinterfl...
问题详情：NextautumnwhenyouseewildgeeseheadingsouthforthewinterflyinginaVformation,youmightthinkaboutwhatscientistshavediscoveredastowhytheyflythatway.Aseachbirdflapsitswings,itcreatesuplift(提升)forthe...