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.carry 　　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

　　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.carry 　　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