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 dont 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.　　The backpacks electricity-creating powers depend on springs used to hang a cloth pack from its metal frame. The frame sits against the wearers 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.　　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 arent on the market yet, but if you do get one eventually, just make sure to look both ways before crossing the street!　　backpack n.背包 watt n. 瓦　　night-vision goggle 夜視鏡 oscillation n. 擺動　　vertical adj. 垂直的 mountaineer n. 登山運動員　　注釋：　　2.Philadelphia：費城[美國賓夕法尼亞州東南部港市]　　4.Mass.：Massachusetts 的縮寫：馬薩諸塞州，美國東北部的一個州?！　?.Science：美國的 Science 雜志為國際上著名的自然科學綜合類學術期刊，在世界學術界享有盛譽。 Science 雜志創刊于1880年，該雜志具有資訊雜志和學術期刊的雙重特點，每周除向世界各地發布有關科學技術和科技政策的重要資訊外，還發表全球科技研究最顯著突破的研究論文和報告。　　1. Backpacks are convenient because　　B) they can hold as many things as you want to carry.　　D) you do not have to carry things with you.

　　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 dont 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.　　The backpacks electricity-creating powers depend on springs used to hang a cloth pack from its metal frame. The frame sits against the wearers 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.　　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 arent on the market yet, but if you do get one eventually, just make sure to look both ways before crossing the street!　　backpack n.背包 watt n. 瓦　　night-vision goggle 夜視鏡 oscillation n. 擺動　　vertical adj. 垂直的 mountaineer n. 登山運動員　　注釋：　　2.Philadelphia：費城[美國賓夕法尼亞州東南部港市]　　4.Mass.：Massachusetts 的縮寫：馬薩諸塞州，美國東北部的一個州?！　?.Science：美國的 Science 雜志為國際上著名的自然科學綜合類學術期刊，在世界學術界享有盛譽。 Science 雜志創刊于1880年，該雜志具有資訊雜志和學術期刊的雙重特點，每周除向世界各地發布有關科學技術和科技政策的重要資訊外，還發表全球科技研究最顯著突破的研究論文和報告?！　?. Backpacks are convenient because　　B) they can hold as many things as you want to carry.　　D) you do not have to carry things with you.