【江西省上饶市2014高考英语二模试题】PeoplewhodonotgetenoughvitaminAintheirdietmaydevelopnightblindness.ButinthedevelopingworldalackofvitaminAcausesmuchmoreseriousharmtochildren.TheWorldHealthOrganizationlinksthelackofvitaminAtoasmanyas250.000childdeathseveryyear.OneexcellentsourceofvitaminAisfoundinsweetpotatoeswithorangeflesh.Orangesweetpotatoescontainhighlevelsofbeta-carotene(胡萝卜素),whichourbodycanchangeintovitaminA.Expertssayorangesweetpotatoesspeciallybred(育种,培植)forgrowingconditionsinAfricacouldhelpsolvethelackofvitaminAthere.But,first,morepeoplewillneedtobepersuadedtoeatthem.JanLowwiththeInternationalPotatoCenter,aresearchorganizationsaysthesweetpotatoneedsabetterimageinAfrica.JanLowsays,…Wedohaveanimageproblemwithsweetpotatoingeneralinsub-SaharanAfrica.Itisseenasacropofthepoor."MsLowexplainsthatsweet