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.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.the

　　1.【答案】D

　　【解析】因其后接形容词powerful作表语故应填系词。shown不是系词;been和appeared虽可作系词但与句意不符;而proved可作系词，意为“证明是”，符合句意。

　　2.【答案】C

　　【解析】根据意思判断，beyond意为“超出，超过”。

　　3.【答案】B

　　【解析】因land on意为“使……着陆”,而send, take和carry表示“把……送到……上去”时,常接介词to,故应选land.

　　4.【答案】A

　　【解析】根据意思判断，travelers正确.

　　5.【答案】C

　　【解析】原句是表示让步的状语从句，而且是一个倒装句，故只能选C as。

　　6.【答案】D

　　【解析】根据词的意思区分，invented(指发明)合乎题意。

　　7.【答案】D

　　【解析】该句为which引导的定语从句，意为“中国发明火箭是在距今800多年前。”句中谓语是一般过去时，故应选D. ago。

　　8.【答案】D

　　【解析】根据句子意思判断，burned正确。

　　9.【答案】B

　　【解析】change into是固定短语，“变成”的意思。

　　10.【答案】C

　　【解析】根据句子意思判断，应选expanding gas膨胀的气体。

　　11.【答案】D

　　【解析】through的意思为“穿过，通过”。

　　12.【答案】C

　　【解析】faces意为“朝着”。

　　13.【答案】D

　　【解析】transmit意为“传递”，disperse意为“驱散”，erect意为“直立，挺直”，radiate意为“辐射，向各方向伸展”，只有D最合题意。

　　14.【答案】D

　　【解析】根据句子意思判断，应为push“推”。

　　15.【答案】C

　　【解析】朝相反的方向，故选C。

　　16.【答案】B

　　【解析】when引导的定语从句。

　　17.【答案】C

　　【解析】根据句子意思判断, follow在这里是遵循的意思。

　　18.【答案】A

　　【解析】根据句子意思判断，describe是“记载描述”的意思。

　　19.【答案】D

　　【解析】for是“对于”的意思。

　　20.【答案】B

　　【解析】根据上下文,只能用不定冠词an。