阅读下面短文，从每题所给的四个选项中选出最佳答案.

Fishhaveears.Really.They'requitesmallandhavenoopeningtotheoutsideworldcarryingsoundthroughthebody.ForthepastsevenyearsSimonThorroldauniversityprofessorhasbeenexaminingfishearssmallroundearbonescalledotoliths.

Asfishgrowsodotheirotoliths.Eachdaytheirotolithsgainaringofcalciumcarbonate（碳酸钙）.Bylookingthroughamicroscope（显微镜）andcountingtheseringsThorroldcandeterminetheexactageofayoungfish.Asafishgetsolderitsotolithsnolongergetdallyrings.Insteadtheygetyearlyringswhichcanalsobecountedgivinginformationaboutthefish'sagejustlikethegrowthringsofatree.

Ringcountingisnothingnewtofishscientists.ButThorroldhasturnedtoanewdirection.They'reexaminingthechemicalelements（元素）ofeachotolithring.

Thedailyringgivesusthetimebutchemistrytellsusabouttheenvironmentinwhichthefishswamonanygivenday.Theseelementstellusaboutthechemistryofthewaterthatthefishwasin.Italsosayssomethingaboutwatertemperaturewhichdetermineshowmuchoftheseelementswillgatherwithineachotolithring.

Thorroldcantellforexampleifafishspenttimeintheopenoceanbeforeenteringthelesssaltywaterofcoastalareas.Hecanbasicallytellwherefisharespendingtheirtimeatanygivenstageofhistory.

InthecaseoftheAtlanticcroakerapopularsaltwaterfoodfishThorroldandhisassistanthavesuccessfullyfollowedthetravellingofyoungfishfrommid-oceantothecoastajourneyofmanyhundredsofmiles.

Thisisimportanttomanagersinthefishindustrywhoknownearlynothingaboutthewhereaboutsoftheyoungfishformostfoodfishintheocean.EagertolearnabouthistechnologyfishscientistsarenowlendingThorroldtheirears.

（1）Whatcanwelearnaboutfishearsfromthetext?

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A.Theyaresmallsoftrings.

B.Theyarenotseenfromtheoutside

C.Theyareopeningsonlyonfoodfish.

D.Theyarenotusedtoreceivesound.

（2）Whydoesthewritercomparethefishtotrees?

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A.Treesgainagrowthringeachday.

B.Treesalsohaveotoliths.

C.Theirgrowthringsare