Mostpeoplewouldsaytheseaisblueandgreen.ButthepeoplewholivenearthecoastofZhejiangmaysayitisred.Itisnotpeoplewhocausedthecolourchangebutverysmalllivingthinginthesea.Theyarealgae(藻类)andprotozoa(原生动物).Theycomeinmanydifferentcolours:redyelloworbrown.Redistheeasiestofthosetoseesowhenthishappenspeoplecallita“redtide.”

Redtidesonlyhappenwhenconditionsintheseaareright.Inthepastfewyearsfactoriesandpeoplehavebeenputtingmorechemicalsintothesea.Thesechemicalshelpalgaeandprotozoatogrowveryquickly.Thetemperatureoftheseaisalsoimportant.Redtidesusuallyhappenat20to30degreesCelsius(摄氏度).Redtidesoftenhappenindrywarmareaswherethereislittlewind.Livingthingsgroweasilyintheseplaces.Sometimesfishermenhelpredtidesbymistake.Theyputsmallseaanimalsintothewaterforfoodtohelpfishgrow.

Thoselivingthingsdomorethanchangethecolourofthewater-theyalsoputpoisonandmucus(黏液)intothesea.Thisishadforfish.Thepoisonisbadfortheirbrains.Andtoomuchmucusintheseafillsupfish’sgills(鳃)sotheycan’t______.LotsofdeadfishandotherseaanimalsarenowwasheduponChinesebeaches.

Redtidescanbebadforpeopletoo.Weshouldn’teatfishfromred-tidewaters.Thealgaegetsinsideoffishanditsmellsbad.Itcanmakeyoureyeswater.Ifpeopleeatfishwithtoomuchalgaeinsidetheycoulddie.

FishermeninZhejiangarehavingahardtimerightnow.Becauseoftheredtidetheyareselling30%lessfreshseafoodthanusual.

InChinaredtidesusuallyhappeninMayandJunearoundplaceslikeFujianGuangdongandHongKong.

Manyothercountriessometimesalsohaveredtides.Butitseemsthatwehavefewwaystostopredtides.Theycanlastaslongas16months.

(以下是A种题型)

46.Whatcancausethewaterintheseatochangeitscolour?

A.Algae. B.Protozoa.

C.Algaeandprotozoa D.Peopleandanimals

47.WhichofthefollowingisNOTtrue?

A.Fishermenintheareaselllessfreshseafoodthanusual

B.Peoplecoulddieiftheyeatfishwithtoomuchalgaeinside.

C.Eatingfishwithalgaeinthemcanmakepeople’seyeswater.

D.Algaeandprotozoac