ElectricBackpack
Backpacks are convenient. They can hold your books，your lunch，and achange of clothes，leaving your hands free to do other things.Someday，if youdont mind carrying a heavy load，your backpacks might also power your MP31player，keep your cell phone running，and maybe even light your wayhome.
The backpacks electricity-creating powers depend onsprings used to hang a cloth pack from its metal frame.The frame sits againstthe wearers back，and the whole pack moves up and down as the person walks.Agear mechanism converts vertical movements of the pack to rotary motions of anelectrical generator，producing up to 7.4 watts.
The backpack could be especially useful forsoldiers，scientists，mountaineers，and emergency workers who typically carryheavy backpacks.For the rest of us，power-generating backpacks could make itpossible to walk，play video games，watch TV，and listen to music，all at the sametime.Electricity-generating packs arent on the market yet，but if you do get one eventually，just make sure to look both ways before crossing thestreet!
backpackn.背包 wattn.瓦
night-visiongoggle 夜视镜 oscillationn.摆动
verticaladj.垂直的 mountaineern.登山运动员5rEutEri p
练习：
A they can be verylarge.
C your handsare freed to do other things.
What is the most important feature of the backpack invented byLawrence C.Rome
A It produces electricity forelectronic devices while the wearer walks.
C It is small andconvenient.
The word springs inParagraph 3 means
B the season of the year，occurring between winter and summer.
D a length of metal woundaround，which returns to its original shape after
According to Paragraph 4，what does Rome plan to do?
B To put the backpack on the market.
D To promote the backpack in anewspaper or on television.
ways before crossing the street!?
B Enjoyingelectronic devices while walking may invite traffic accidents.
D It is wise of you to have such abackpack.
C第一段告诉我们，因为背包可以装许多东西，所以可以将双手解放出来做其他事情：tofree your hands to do other things。
D springs在此是弹簧的意思。spring是一个多义词：泉水、春天、弹跳。
B这个句子的字面意思是：如果你终于得到这样的背包，过马路时一定要两面都看看。也就是说，不要因为同时玩着游戏，听着音乐、看着电视，太专注以致不注意来往车辆了