Canyouimaginetravelingtoworkinaone-mansubmarine?

Scientistsbelievethatsomedayone-mansubmarineswillbeasnumerousasautomobilestoday.Onesays “Onedaysoon menwillwalkontheoceanfloorastheydoonthestreet.”Perhapsduringyourlifetime peoplewilltravel workandliveunderthesea.

Shipscarryingoilandarticlesoftradewillmovebeneaththeocean.Passengershipswillbebuilttotravelunderwater wherestormscannotdelaythemormakepeopleseasick.Specialunderwatershipswillbedesignedformining fishing andexploringunknownareas.Formilitaryuse theremaybesubmarinesthatcanflyandthendiveunderwatertoapproachthebattleareawithoutbeingseen.

Firsthoweverthehumanproblemsassociatedwithlivingintheoceanwillneedtobestudiedindetail.Manyoftheseproblemsarethesameastheproblemsoflivinginouterspace:pressurelackofoxygenandweightlessness.Alreadyscientistshavebeguntostudytheseproblems.

In1963and1964scientistsandnavydiverslivedandworkedunderwaterforseveraldaysintwoprojectswhichwerecalledSealabⅠandSealabⅡ.TheSealabⅡexperimentkeptthescientistsanddivers215feetbelowthesurfaceforthirtydaysstudyingmarinebiology temperature pressure currents andoceanbottomgeology.

Manypuzzlingquestionsremainunanswered however.Man’swarmbloodmakesitdifficultforhimtolivelongintheseawithoutsomekindsofwarmth.Canourbloodbechangedtofitnewwatersurroundings? Whatwillhappentoourmusclesifweliveinthewaterverylong? Willtheybecomesoftawayfromourusuallandexistence? Willbonesbecomeweakandourbloodpressurechange? Scientistsaresearchingforanswers.

Bystudyingplantsandanimalsdeepintheocean scientistsmayfindacureforsomeofourmostserioushumandiseases.Wemaylearntouseplantstoincreaseourworldfoodsupply.Engineersmaylearntousethepoweroftheseabybuildinghugewallstocatchtheforceofthetides.

61.Inthepassagetheauthoristalkingtousabouttheproblemsof______.

A.pressurelackofoxygenandweightlessnessinthesea

B.livingworkingbelowtheocean

C.underwatersubmarine

D.walkingontheoceanfloor

62.