阅读下面短文，根据短文内容，在短文后面小题中句子空白处填入适当的词语或句子。

Weknowthatmanyanimalsdonotstayinoneplace．Birdsfishandotheranimalsmovefromoneplacetoanotherplaceatacertaintime．Theymovefordifferentreasons：mostofthemmovetofindfoodmoreeasilybutothersmovetogetawayfromplacesthataretoocrowded．

Whencoldweathercomesmanybirdsmovetowarmerplacestofindfood．Somefishesgivebirthinwarmwaterandmovetocoldwatertofeed．Themostfamousmigrationisprobablythemigrationoffishwhichiscalled“salmon”(鲑鱼)．Thisfishisborninfreshwaterbutittravelsmanymilestosaltwater．Thereitspendsitslife．Whenitisolditreturnstoitsbirthplaceinfreshwater．Thenitgivesbirthanddies．InnorthernEuropethereisakindofmouse．Theyleavetheirmountainhomeswhentheybecometoocrowded．Theymovedowntothelowland．Sometimestheymoveallthewaytotheseasideandmanyofthemarekilledwhentheyfallintothesea．

Recentlyscientistshavestudiedthemigrationofakindoflobster(龙虾)．Everyyearwhentheseasonofthebadweatherarrivesthelobstersgetintoalonglineandstarttowalkacrosstheflooroftheocean．Nobodyknowswhytheydothisandnobodyknowswheretheygo．Sosometimesweknowwhyhumansandanimalsmovefromoneplacetoanotherplacebutatothertimeswedon’t．Maybelivingthingsjustliketotravel．

1．Thereasonformostoftheanimalstomoveis________．

2．Findthewordinthepassagewhichmeans“themovementfromoneplacetoanotherofalargegroupofanimals”andwriteitdownhere：________．

3．Theunderlinedword“There”inthesecondparagraphrefersto(指的是)________．

4．Thesalmoncomesbacktoitsbirthplaceinorderto________．

5．Thelobstersbegintomovetoanotherplacewhen________．