阅读理解:
Beforeanewtypeofairplanegoesintoservice,everypartofitistestedagainandagain.Buttherearetwoteststhataremoreimportantthanalltheothers.
Thefirstiscalledthe“tanktest”.Amodernairplanemustflyveryhighinthesky.Airmustbepumpedintotheplanesothatthepassengerscanbreathe.Themetalstructureoftheplanehastobeverystrongforthisreason.Whentheplaneisfilledwithair,theairpressesagainsttheskinoftheplaneinside.Thepressureonasmallwindowislikeahugefootthatistryingtogetout.Ifasmallpartoftheplaneweretofail,theplanewouldexplodeinthesky.Totestthestructureoftheplane,theplaneisloweredintoahugetankorcontainerofwater.Thenitisfilledwithair.Thepressureinsidetheplaneisgreaterthaniteverwillbewhenitishighupintheair.Finally,thereisanexplosion.Thisdoesnotcausesomuchdamageinsidethewatertankasitwouldanywhereelse.Engineerscandiscoverwhichpartoftheplanehasbroken.Thenthatpartismadestronger.
Themostdangeroustesthappenswhenthenewplaneisgoingthroughtestflightsintheair.Thetestpilotmustfindoutexactlywhathappenswhentheenginesareallshutoffatonce.Theplanebeginstofalllikeastone.Itisthepilot'sjobtofindouthowhecangetcontroloftheplaneagain.Thesetwotestsareexamplesofhowplanesaremadesafebeforetheyevercarrypassengers.
1.Bydoingthe“tanktest”,theengineerscanfindout________.
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A.theamountofairintheplane
B.thestrengthoftheplanestructure
C.thepressureinsideandoutsidetheplane
D.thepoweroftheairplaneengines
2.Whatwillhappentotheplaneunderthe“tanktest”?
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A.Itwillbebroken.
B.Itwillbemadestronger.
C.Itwillbefilledwithwater.
D.Itwillbetestedbypilots.
3.Accordingtothetext,whyaretestflightsmostdangerous?
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A.Theplanemayexplodeintheair.
B.Thepilotmaylosecontroloftheplane.
C.Theenginesmaybedamaged.
D.Toomuchairmaygetintotheplane.
4.Whatmightbethemostsuitabletitleforthetext?
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A.TwoImportantTestsonAirplanes
B.TheImportanceofFlyingSafely
C.TheDangerofTestingAirplanes
D.HowAirplanesAreMadeandTested