閱讀下面的短文。每篇短文的后面有五個問題，每個問題有四個備選答案。請根據(jù)短文的內(nèi)容選擇答案。
Electric Backpack
Backpacks are convenient． They can hold your books，your lunch，and a change of clothes，leaving your hands free to do other things．Someday，if you don't mind carrying a heavy load，your backpacks might also power your MP31 player，keep your cell phone running，and maybe even light your way home．
Lawrence C． Rome and his colleagues from the University of Pennsylvania in Philadelphia2 and the Marine Biological Laboratory in Woods Hole3，Mass．4，have invented a backpack that makes electricity from energy produced while its wearer walks． In military actions，search-and-rescue operations，and scientific field studies，people rely increasingly on cell phones，global positioning system (GPS) 5 receivers，night-vision goggles，and other battery powered devices to get around and do their work． The backpack’s electricity- generating feature could dramatically reduce the amount of a wearer’s load now devoted to spare batteries，report Rome and his colleagues in the Sept．9 Science6．
The backpack’s electricity-creating powers depend on springs used to hang a cloth pack from its metal frame．The frame sits against the wearer’s back，and the whole pack moves up and down as the person walks．A gear mechanism converts vertical movements of the pack to rotary motions of an electrical generator，producing up to 7．4 watts．
Unexpectedly，tests showed that wearers of the new backpack alter their gaits in response to the pack’s oscillations，so that they carry loads more comfortably and with less effort than they do ordinary backpacks． Because of that surprising advantage，Rome plans to commercialize both electric and non-electric versions of the backpack．
The backpack could be especially useful for soldiers，scientists，mountaineers，and emergency workers who typically carry heavy backpacks．For the rest of us，power-generating backpacks could make it possible to walk，play video games，watch TV，and listen to music，all at the same time．Electricity-generating packs aren’t on the market yet，but if you do get one eventually，just make sure to look both ways before crossing the street!
詞匯:
backpack / 5bAkpAk / n．背包 watt / wCt / n．瓦（特）
receiver / ri5si:vE(r) / n．接收機 gait/ ^eit / n．步態(tài)，步法
night-vision goggle 夜視鏡 oscillation / 7Csi5leiFEn / n．擺動
spring / spriN / n．彈簧 commercialize/ kE5mE:FElaiz / v．商業(yè)化
vertical / 5vE:tikEl / adj．垂直的 mountaineer/ 7maunti5niE(r) / n．登山運動員
rotary / 5rEutEri / adj．旋轉(zhuǎn)的
練習：
1． Backpacks are convenient because
A they can be very large．
B they can hold as many things as you want to carry．
C your hands are freed to do other things．
D you do not have to carry things with you．
2． What is the most important feature of the backpack invented by Lawrence C．Rome
and his colleagues?
A It produces electricity for electronic devices while the wearer walks．
B It can be used as cell phones，GPS in the military actions or field studies．
C It is small and convenient．
D It is light and easy to carry．
3． The word "springs" in Paragraph 3 means
A a small stream of water flowing naturally from the earth．
B the season of the year，occurring between winter and summer．
C the act or an instance of jumping or leaping．
D a length of metal wound around，which returns to its original shape after
being pushed．
4． According to Paragraph 4，what does Rome plan to do?
A To make the backpack more comfortable for the wearer．
B To put the backpack on the market．
C To test the advantage of the backpack．
D To promote the backpack in a newspaper or on television．
5． What is implied in “if you do get one eventually，just make sure to took both
ways before crossing the street !”?
A You will be too excited to watch the traffic．
B Enjoying electronic devices while walking may invite traffic accidents．
C It is not possible for you to get such a backpack．
D It is wise of you to have such a backpack．
答案與題解：
1． C 第一段告訴我們，因為背包可以裝許多東西，所以可以將雙手解放出來做其他事情：to free your hands to do other things。
2． A 第二段的第一句說，Lawrence C．Rome及其同事們發(fā)明的這種背包，當背著背包走路時，會有電能產(chǎn)生；該段最后一句告訴我們，背包的這種性能可減少背包的重量，因為不必攜帶備用電池。
3． D “springs"在此是彈簧的意思。spring是一個多義詞：泉水(A)、春天(B)、彈跳(C)。
4． B 第四段最后一句的意思是：Rome計劃將這種背包商業(yè)化，即推向市場。A、C、D在文中均未提到。D的意思是為背包做廣告。
5． B 這個句子的字面意思是：如果你終于得到這樣的背包，過馬路時一定要兩面都看看。也就是說，不要因為同時玩著游戲，聽著音樂、看著電視，太專注以致不注意來往車輛了。
Electric Backpack
Backpacks are convenient． They can hold your books，your lunch，and a change of clothes，leaving your hands free to do other things．Someday，if you don't mind carrying a heavy load，your backpacks might also power your MP31 player，keep your cell phone running，and maybe even light your way home．
Lawrence C． Rome and his colleagues from the University of Pennsylvania in Philadelphia2 and the Marine Biological Laboratory in Woods Hole3，Mass．4，have invented a backpack that makes electricity from energy produced while its wearer walks． In military actions，search-and-rescue operations，and scientific field studies，people rely increasingly on cell phones，global positioning system (GPS) 5 receivers，night-vision goggles，and other battery powered devices to get around and do their work． The backpack’s electricity- generating feature could dramatically reduce the amount of a wearer’s load now devoted to spare batteries，report Rome and his colleagues in the Sept．9 Science6．
The backpack’s electricity-creating powers depend on springs used to hang a cloth pack from its metal frame．The frame sits against the wearer’s back，and the whole pack moves up and down as the person walks．A gear mechanism converts vertical movements of the pack to rotary motions of an electrical generator，producing up to 7．4 watts．
Unexpectedly，tests showed that wearers of the new backpack alter their gaits in response to the pack’s oscillations，so that they carry loads more comfortably and with less effort than they do ordinary backpacks． Because of that surprising advantage，Rome plans to commercialize both electric and non-electric versions of the backpack．
The backpack could be especially useful for soldiers，scientists，mountaineers，and emergency workers who typically carry heavy backpacks．For the rest of us，power-generating backpacks could make it possible to walk，play video games，watch TV，and listen to music，all at the same time．Electricity-generating packs aren’t on the market yet，but if you do get one eventually，just make sure to look both ways before crossing the street!
詞匯:
backpack / 5bAkpAk / n．背包 watt / wCt / n．瓦（特）
receiver / ri5si:vE(r) / n．接收機 gait/ ^eit / n．步態(tài)，步法
night-vision goggle 夜視鏡 oscillation / 7Csi5leiFEn / n．擺動
spring / spriN / n．彈簧 commercialize/ kE5mE:FElaiz / v．商業(yè)化
vertical / 5vE:tikEl / adj．垂直的 mountaineer/ 7maunti5niE(r) / n．登山運動員
rotary / 5rEutEri / adj．旋轉(zhuǎn)的
練習：
1． Backpacks are convenient because
A they can be very large．
B they can hold as many things as you want to carry．
C your hands are freed to do other things．
D you do not have to carry things with you．
2． What is the most important feature of the backpack invented by Lawrence C．Rome
and his colleagues?
A It produces electricity for electronic devices while the wearer walks．
B It can be used as cell phones，GPS in the military actions or field studies．
C It is small and convenient．
D It is light and easy to carry．
3． The word "springs" in Paragraph 3 means
A a small stream of water flowing naturally from the earth．
B the season of the year，occurring between winter and summer．
C the act or an instance of jumping or leaping．
D a length of metal wound around，which returns to its original shape after
being pushed．
4． According to Paragraph 4，what does Rome plan to do?
A To make the backpack more comfortable for the wearer．
B To put the backpack on the market．
C To test the advantage of the backpack．
D To promote the backpack in a newspaper or on television．
5． What is implied in “if you do get one eventually，just make sure to took both
ways before crossing the street !”?
A You will be too excited to watch the traffic．
B Enjoying electronic devices while walking may invite traffic accidents．
C It is not possible for you to get such a backpack．
D It is wise of you to have such a backpack．
答案與題解：
1． C 第一段告訴我們，因為背包可以裝許多東西，所以可以將雙手解放出來做其他事情：to free your hands to do other things。
2． A 第二段的第一句說，Lawrence C．Rome及其同事們發(fā)明的這種背包，當背著背包走路時，會有電能產(chǎn)生；該段最后一句告訴我們，背包的這種性能可減少背包的重量，因為不必攜帶備用電池。
3． D “springs"在此是彈簧的意思。spring是一個多義詞：泉水(A)、春天(B)、彈跳(C)。
4． B 第四段最后一句的意思是：Rome計劃將這種背包商業(yè)化，即推向市場。A、C、D在文中均未提到。D的意思是為背包做廣告。
5． B 這個句子的字面意思是：如果你終于得到這樣的背包，過馬路時一定要兩面都看看。也就是說，不要因為同時玩著游戲，聽著音樂、看著電視，太專注以致不注意來往車輛了。