阅读理解。

Haveyoueverwonderedwhybirdssing?Maybeyouthoughtthattheywerejusthappy.Afterallyou

probablysingorwhistlewhenyouarehappy.

Somescientistsbelievethatbirdsdosingsomeofthetimejustbecausetheyarehappy.Howeverthey

singmostofthetimeforaverydifferentreason.Theirsingingisactuallyawarningtootherbirdstostay

outoftheirterritory.

Doyouknowwhata"territory"is?Aterritoryisanareathatananimalusuallythemaleclaims(声称)

asitsown.Onlyheandhisfamilyarewelcomethere.Nootherfamiliesofthesamespecies(物种)are

welcome.Youryardandhouseareyourterritorywhereonlyyourfamilyandfriendsarewelcome.Ifa

strangershouldenteryourterritoryandthreatenyouyoumightshout.Probablythiswouldbeenoughto

frightenhimaway.

Ifsoyouhaveactuallyscaredthestrangerawaywithouthavingtofighthim.Abirddoesthesamething.

Butheexpectsanoutsideralmostanytimeespeciallyatnesting(筑巢)season.Soheisscreamingallthe

timewhetherhecanseeanoutsiderornot.Thisscreamingiswhatwecallabird'ssonganditisusually

enoughtokeepanoutsideraway.

Birdssingloudestinthespringwhentheyaretryingtoattractamateandwarnothersnottoenterthe

territoryoftheirs.

Youcanseethatbirdshavealanguagealltheirown.Mostofithastodowithattractingmatesandsetting

upterritories.

1.Somescientistsbelievethatmostofthetimebirds'singingisactually_____.

A.anexpressionofhappiness

B.awayofwarning

C.anexpressionofanger

D.awayofgreeting

2.Whatisabird's"territory"?

A.Aplacewherefamiliesofotherspeciesarenotaccepted.

B.Aplacewhereabirdmayshoutatthetopofitsvoice.

C.Anareaforwhichbirdsfightagainsteachother.

D.Anareawhichabirdconsiderstobeitsown.

3.Whydobirdskeeponsingingatnestingseason?

A.Becausetheywanttoinvitemorefriends.

B.Becausetheirsinginghelpsfrightenoutsidersaway.

C.Becausetheywanttofindoutsidersaround.