The rocket engine, with its steady roar like that of a waterfall or a thunderstorm, is an impressive symbol of the new space age.Rocket engines have __1__ powerful enough to shoot astronauts __2__ the earth's gravitational pull and __3__ them on the moon.We have now become __4__ space.
　　Impressive and complex __5__ it may appear, the rocket, which was __6__ in China over 800 years __7__ , is a relatively simple device.Fuel that is __8__ in the rocket engine changes __9__ gas.The hot and rapidly __10__ gas must escape, but it can do so only __11__ an opening that __12__ backward.As the gas is __13__ with great force, it __14__ the rocket in the __15__ direction.Like the kick of a gun __16__ it is fired, it __17__ the laws of nature __18__ by Sir Isaac Newton when he discovered that“ __19__ every action, there is __20__ equal and opposite reaction.”
　　1.A.shown B.been C.appeared D.proved
　　2.A.against B.despite C.beyond D.from
　　3.A.send B.land C.take D.carrywww.Ｅxamda.CoM考试就到考试大
　　4.A.travelers B.astronauts C.researchers D.explorers
　　5.A.that B.so C.as D.sometimes
　　6.A.made B.discovered C.developed D.invented
　　7.A.in advance B.before C.earlier D.ago
　　8.A.round B.contained C.stored D.burned
　　9.A.as B.into C.for D.the
　　10.A.heating B.escaping C.expanding D.conducting
　　11.A.in B.at C.by D.through
　　12.A.turns B.goes C.faces D.directs
　　13.A.transmitted B.dispersed C.erected D.radiated
　　14.A.attracts B.leads C.pulls D.pushes
　　15.A.same B.other C.opposite D.wrong
　　16.A.that B.when C.if D.although
　　17.A.states B.proves C.follows D.breaks
　　18.A.described B.discussed C.considered D.made
　　19.A.like B.as C.with D.for
　　20.A.no B.an C.another D.theCloze
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