阅读理解。

Weknowthatmanyanimalsdonotstayinoneplace.Birdsfishandotheranimalsmovefromoneplace

toanotheratacertaintime.Theymovefordifferentreasonsmostofthemmovetofindfoodmoreeasily

butothersmovetogetawayfromplacesthataretoocrowded.Whencoldweathercomesmanybirdsmove

towarmerplacestofindfood.Somefishesgivebirthinwarmwaterandmovetocoldwatertofeed.The

mostfamousmigration(迁移)isprobablythemigrationofthefishwhichiscalled"salmon".Thisfishisborn

infreshwaterbutittravelsmanymilestosaltwater.Thereitspendsitslife.Whenitisolditreturnstoits

birthplaceinfreshwater.Thenitgivesbirthanddiesthere.InnorthernEuropethereisakindofmice.They

leavetheirmountainhomeswhentheybecometoocrowded.Theymovedowntothelowland.Sometimes

theymoveallthewaytotheseasideandmanyofthemarekilledwhentheyfallintothesea.

Recentlyscientistshavestudiedthemigrationofakindoflobsters(龙虾).Everyyearwhentheseason

ofbadweatherarrivesthelobstersgetintoalonglineandstarttowalkacrosstheflooroftheocean.Nobody

knowswhytheydothisandnobodyknowswheretheygo.Sosometimesweknowwhyhumansandanimals

movefromoneplacetoanotherbutatothertimeswedon't.Maybelivingthingsjustliketotravel.

1.Mostanimalsmovefromoneplacetoanotheratacertaintimeto_____.

[ ]

A.givebirth

B.enjoywarmerweather

C.findfoodmoreeasily

D.findbeautifulplaces

2.Thefishcalled"salmon"spendsalonglifein_____.

[ ]

A.saltwater

B.rivers

C.freshwater

D.itsbirthplace

3.ThemiceinnorthernEuropemovewhen_____.

[ ]

A.theygivebirth

B.theweatherisbad

C.theplacegetstoocrowded

D.theyhaven'tenoughfood

4.Thelobstersmove_____.

[ ]

A.tothefreshwater

B.totheseafloor

C.atacertaintime

D.tofindmorefood

5.Whatisthemainideaofthepassage?

[ ]

A