首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
考研
Sunlight is free, but that is no reason to waste it. Yet even the best silicon solar cells—by far the most【C1】________ sort—conv
Sunlight is free, but that is no reason to waste it. Yet even the best silicon solar cells—by far the most【C1】________ sort—conv
admin
2023-04-14
64
问题
Sunlight is free, but that is no reason to waste it. Yet even the best silicon solar cells—by far the most【C1】________ sort—convert only a quarter of the light that falls on them. Silicon has the【C2】________of being cheap: manufacturing improvements have brought its price to a point where it is snapping at the heels of fossil fuels.【C3】________many scientists would like to replace it【C4】________something fundamentally better.
John Rogers, of the University of Illinois, Urbana-Champaign, is one. The cells he has【C5】________can convert 42.5% of sunlight.【C6】________improved, Dr Rogers reckons, their efficiency could rise to 50%. Their【C7】________is that they are actually not one cell, but four, stacked one on top of another.
Solar cells are made of semiconductors, and every type of semiconductor has a【C8】________called a band gap that is different from that of other semiconductors. The band gap【C9】________the longest wavelength of light a semiconductor can absorb (it is transparent to longer wavelengths). It also fixes the【C10】________amount of energy that can be【C11】________ from shorter wavelength. The result is that long-wavelength photons are lost and short-wave ones incompletely utilised.
Dr Rogers【C12】________this by using a different material for each layer of the stack. He chooses his materials【C13】________ the bottom of the band gap of the top layer matches the top of the band gap of the one underneath, and so on【C14】________ the stack. Each layer thus【C15】________off part of the spectrum, converts it efficiently into electrical energy and passes the rest on.
The problem is that the materials needed to make these semiconductors are【C16】________. But Dr Rogers has found a way to overcome this.【C17】________solar-cell modules are completely covered by semiconductor, but in his only 0.1% of the surface is so covered. The semiconducting stacks, each half a millimeter square, are【C18】________over that surface many dots. Each stack then has a pair of cheap glass lenses【C19】________over it. These focus the sun’s light onto the stack, meaning that all【C20】________light meets a semiconductor.
【C19】
选项
A、hung
B、mounted
C、concealed
D、shielded
答案
B
解析
从本句“每个半导体堆有一对便宜的玻璃镜片……在上面”及后一句“这些镜片把阳光聚焦在半导体堆上”可推出,镜片应“置于”每个反应堆上,故选B项mounted“架置”。A项hung“悬挂”镜片不太可能会悬挂在反应堆上。C项concealed“隐藏”和D项shielded“保护”均为及物动词,不接over。
转载请注明原文地址:https://kaotiyun.com/show/j5MD777K
0
考研英语二
相关试题推荐
ZoeBuhlerwasscheduledforanultrasoundappointmentontheSeptembermorningwhenAustralianpoliceenteredherhome.Thepre
Everyonewantstobeauthentic.Youwanttobetruetoyourself,notaslavishfollowerofsocialexpectations.Youwantto"liv
Everyonewantstobeauthentic.Youwanttobetruetoyourself,notaslavishfollowerofsocialexpectations.Youwantto"liv
Sunlightisfree,butthatisnoreasontowasteit.Yeteventhebestsiliconsolarcells—byfarthemost【C1】________sort—conv
Sunlightisfree,butthatisnoreasontowasteit.Yeteventhebestsiliconsolarcells—byfarthemost【C1】________sort—conv
Notsolongago,itwasthestuffofnightmares:youpickupthelandlinetelephoneandthere’snodialingtone.Nothing.Theph
Notsolongago,itwasthestuffofnightmares:youpickupthelandlinetelephoneandthere’snodialingtone.Nothing.Theph
Notsolongago,itwasthestuffofnightmares:youpickupthelandlinetelephoneandthere’snodialingtone.Nothing.Theph
Notsolongago,itwasthestuffofnightmares:youpickupthelandlinetelephoneandthere’snodialingtone.Nothing.Theph
随机试题
PTOstands______"Pleaseturnoverthepage",ofcourse.
患者小便闭塞,点滴不通,病势较急,应诊断为水肿脾阳虚衰的治法是
太阳中风证,其发热的特点是
A.举止端庄、态度热情B.全面系统、认真细致C.从诊治需要出发、目的合理D.对症下药、剂量安全E.严格掌握手术指征、动机正确询问病史的道德要求是
带传动的主要失效形式之一是带的()。
乘数原理把投资变动看作()。
简述教育心理学的研究内容。
德育过程的实质是()。
【B1】【B19】
A、Moredetailedlabeling.B、Simplelabeling.C、Preciselabeling.D、Basiclabeling.A文章最后提到,如今食品标签必须向消费者提供更为详细的信息,答案为A。
最新回复
(
0
)