Scientistshavebeenpuzzledbythephenomenonthatmigratingbirdsflynotjustingroupsallthetimebutin"V"formationsandtheyhavetriedtofigureoutwhatbenefitbirdsgetfromthisparticularformation.NowaresearchgroupfromUniversityofLondonmayhavefoundtheanswer―migratingbirdsflyina"V"tosaveenergyaccordingtoastudypublishedinthejournalNature.

Whenabirdflaps(振翅)itswingsitstirstheairarounditandcausesittomoveindifferentdirections.Scientistfoundinthestudythattheaircreatesanupward-movingwaveatthetipsofthewingswhichmeansthatifabirdfliesaroundthewingtipsofanotherbirditcangetaboost（抬高）fromtherisingairandthereforeuselessenergytostayintheair.

Apartformthe"freeride"strategyscientistswerealsosurprisedtoobservethatmigratingbirdstimedtheirwingbeatsandadjustedtheirpositionsinaveryprecisewaytomaximizetheliftingeffectwhileavoidingareaswheretheairmovedownward.

"They'reabletosensewhat'sgoingonfromthebirdinfrontwherethis'goodair'iscomingfromandnowhowtopositionthemselvesperfectlyinit"leadresearcherStevenPortugaltoldBBC.

Infactthe"V"formationhaslongthoughttohelpbirdsflymoreefficiently(效率搞地).Apreviousstudyshowedthatbirds'heartrateswentdownwhentheywereflyingtogetherina"V"formation.Jetfighterswerealsofoundtobeablereducetheirenergyusebyupto18%bystayingnearthewingtipsofotherjetfighters.Bothofthesefindingsledscientiststosuspectthatthe"V"formationhadanefficiencypurposebutuntilnowtheystilllackproof.

"Forscientiststhenewstudyprovidesaninsightintoaninterestingnaturalphenomenon.Butitcouldmeanevenmoreforaircraftcompanies—helpingthemunderstandhowtheycanimitatethatwiththeirplaneformationstosavefuelsaidPortugal."

1.Whatistheauthor'spurposeinwritingthisarticle?

A.Toexplainhowbirdsbenefitfrommigration.

B.Tointroducehowmigratingbirdsfindtheirway.

C.Totellsomeapplicationsofmigratingbirds'"V"formations.

D.Toreportnewfindingsaboutmigratingbirds'"V"formations.

2.Accordingtotherecentstudywhenbirdsmigrate.

A.theydon'tchanget