Somescientistssaythatanimalsintheoceanareincreasinglythreatenedbynoisepollutioncausedbyhumanbeings.

 Thenoisethataffectsseacreaturescomesfromanumberofhu?manactivities.Itiscausedmainlybyindustrialunderwaterexplo?sionsoceandrillingsandshipengines.Suchnoisesareaddedtonaturalsounds..Thesesoundsincludethebreakingoficefieldsunderwaterearthquakesandsoundsmadebyanimalsthemselves.

 Decibels(分贝)measuredinwateraredifferentfromthosemeasuredonland.Anoiseofonehundredandtwentydecibelsonlandcausespaintohumanears.Inwateradecibellevelofonehundredandninetyfivewouldhavethesameeffect.

 Somescientistshaveproposedsettinganoiselimitofonehundredandtwentydecibelsinoceans.Theyhaveobservedthatnoisesatthatlevelcanfrightenandconfusewhales.

 AteamofAmericanandCanadianscientistsdiscoveredthatloudernoisescanseriouslyinjuresomeanimals.

Theresearchteamfoundthatpowerfulunderwaterexplosionswerecausingwhalesintheareatolosetheirhearing.Thisseriouslyaffectedthewhales'abilitytoex?changeinformationandfindtheirways.Someofthewhalesevendied.Theexplo?sionshadcausedtheirearstobleedandbecomeinfected.

 Manyresearcherswhoseworkdependsonoceansoundsobjecttoalimitofonehundredandtwentydecibels.Theysaysuchalimitwouldmeananendtoimportantindustrialandscientificresearch.

 Scientistsdonotknowhowmuchandwhatkindsofnoisesareharmfultooceananimals.Howevermanyscientistssuspectthatnoiseisagreaterdangerthantheybelieved.Theywanttopreventnoisesfromharmingcreaturesintheocean.

1.Accordingtothepassagewhichofthefollowingisincreasinglydangeroustoseacreatures?

   A.Thesoundofacar.B.Thesoundofvoices.

   C.Manmadenoisepollution.D.Thesoundofsteps.

2.AccordingtothepassagenaturalsoundsincludeallofthefollowingEXCEPT   

   A.soundsmadebyanimalsthemselves

   B.oceandrillings

   C.underwaterearthquakes

   D.thebreakingoficefields

3.Whichofthefollowingisdiscussedinthethirdparagraph?

   A.Thesa