The rocket engine, with its steady roar like that of a waterfall or athunderstorm, is an impressive symbol of the new spaceage.Rocket engines have 1_ powerful enough to shootastronauts 2_ the earth’s gravitational pull and 3_ them on themoon.We have now become 4_ space.
Impressive and complex 5_ it may appear, the rocket, whichwas 6_ in China over 800 years 7_ , is a relatively simpledevice.Fuel that is 8_ in the rocket engine changes 9_ gas.The hot and rapidly 10 _gas mustescape, but it can do so only 11_ an opening that 12_ backward.As the gas is 13_ with greatforce, it 14_ the rocket in the 15 _direction.Like the kick of a gun 16_ it is fired, it 17_ the laws ofnature 18_ by Sir Isaac Newton when he discovered that“ 19_ every action, there is 20_ equaland 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
