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! 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 withyou.
“化妆品冰箱”大行其道
你能跟着马拉松健将跑多远?快看看“基普桑数字”吧
男用彩妆神器Guyliner
新骗术:老板喊你来办公室
逛商场时被价签吓到休克?
“大爷式占座”惹争议
奥巴马2015国情咨文演讲(双语全文)
美国西北部降“牛奶雨”
各种“替身”的说法
习近平西雅图演讲(双语全文)
心塞就到“微型公园”小憩一下吧
“赞酱”是什么鬼?
小心成为“求赞党”
现在流行“婚前宠物协议”
有类人天生对事实不买账
让你欲罢不能的“超级美味”
献给女孩们的毕业演讲:永远不要因为“是女人”而放弃
专属于自己的me time
快来迎接“小黄人黄”
习近平在博鳌亚洲论坛开幕式上的演讲(双语全文)
穿过草地的“心选小路”
马云纽约经济俱乐部演讲
太伤心进入“避男期”
小心“大脑短路”
桑德伯格清华毕业演讲:命运偏爱勇者
毒舌罗伯特·德尼罗给毕业生的中肯建议
超人气男士发型Man Bun
数据造假新手段“P值黑客”
总觉自己太瘦小?可能是“恐瘦症”
不想打工?来做“个体企业经营者”吧
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |