Scientists from the University of Pennsylvania in Philadelphia and the Marine Biological Laboratory in Woods Hole, Mass., have invented a backpack that makes electricity from energy produced while its wearer walks.
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 mechanism with gears collects energy from this motion and transfers it to an electrical generator.
Surprisingly, the researchers found, people walk differently when they wear the springy packs. As a result, wearers use less energy than when lugging regular backpacks. Also, the way the new packs ride on wearers' backs makes them more comfortable than standard packs, the inventors say.
The backpack could be especially useful for soldiers, scientists, mountaineers, and emergency workers who typically carry heavy backpacks. These people often rely on global positioning system (GPS) receivers, night-vision goggles, arid other battery-powered devices to get around and do their work. Because the pack can make its own electricity, users don't need to give up space in their packs to lots of extra batteries.
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!
The first paragraph hints (暗示) ______.
A.backpacks are convenient
B.someday backpacks can generate electricity
C.MP3 players and cell phones can also be put into a backpack
D.backpacks hold things for people so as to free their hands to do other things.
第1题
A.固定价格,附加币值调整
B.固定酬金 (固定目标 )
C.固定成本
D.成本加酬金
第2题
A.固定价格,附加币值调整
B.固定酬金(固定目标)
C.固定价格
D.成本加酬金
第3题
A.固定价格,依据经济价格调整
B.固定价格激励(固定目标)
C.固定价格
D.成本加奖励
第4题
A.成本加激励费用合同CPIF
B.固定总价合同FFP
C.总价加激励费用合同FPIF
D.成本加固定费用合同CPFF
第5题
A.能作商业价格调整的固定价格
B.固定价格加激励(固定的目标)
C.绝对固定价格
D.成本加奖励费
第6题
你负责保证你的供货商正确履行合同。为了对合同进行有效的管理,你应该:
A.举行投标人会议
B.选举合同的合同形式
C.执行合同变更控制制度
D.准备工作陈述
第7题
A.仔细阅读合同看看是否有办法取消合同
B.寻找另一个供货商,取消和当前供货商的合同
C.和供货商协商如果一次购买更多产品,但年度购买次数减少是否可以降低成本,然后和主管讨论这种新的方法
D.会见你主管的经理汇报这种情况
第8题
A.仔细阅读合同看看是否有办法取消合同
B.寻找另一个供货商,取消和当前供货商的合同
C.和供货商协商如果一次购买更多产品,但年度购买次数减少是否可以降低成本,然后和主管讨论这种新的方法
D.会见你主管的经理汇报这种情况
第9题
A.仔细阅读合同看看是否有办法取消合同
B.寻找另一个供货商,取消和当前供货商的合同
C.和供货协商如果一次购买更多产品,但年度购买次数减少是否可以降低成本,然后和主管讨论这种新的
D.会见你的主管的经理汇报这种情况
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