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
外语
A scientific discovery is often made【C1】______ before someone is able to put it to use.【C2】______ , scientists discovered how to
A scientific discovery is often made【C1】______ before someone is able to put it to use.【C2】______ , scientists discovered how to
admin
2009-02-10
19
问题
A scientific discovery is often made【C1】______ before someone is able to put it to use.【C2】______ , scientists discovered how to split atoms decades【C3】______ the invention of the atomic bomb and the use of【C4】______ power to produce electricity. But sometimes discovery and【C5】______ happen at the same time, as occurred more than thirty years ago【C6】______ the discovery of coherent light and the invention of the laser.
The word laser【C7】______ "light amplification by stimulated emission of radiation. To many people, lasers are very mysterious, but a laser is simply a【C8】______ that produces a strong light. The light from the laser is called【C9】______ light because it is light that only moves in one direction.【C10】______ , incoherent light, like the light from the sun or light from a bulb, moves away from its source【C11】______ all directions, so its strength is very spread out. The light from a laser, moving in only one direction and【C12】______ in a narrow beam, is much stronger. Laser light is created by a【C13】______ called stimulated emission. In this process, the atoms of a certain substance, such as a crystal or a gas, are excited 【C14】______ that they produce coherent light. A person working with a laser can aim this coherent light,【C15】______ a laser beam, in any direction.
As soon as the laser was developed, scientists began thinking of practical applications【C16】______ it. One of the earliest uses was to make extremely precise measurements of distance and speed.【C17】______ , the distance to the moon was measured to within a foot, and the speed of light was measured to 【C18】______ a thousandth of a mile per second. As time【C19】______ , many more applications for the laser were【C20】______ .
【C3】
选项
A、by
B、before
C、after
D、since
答案
B
解析
此题考查表示时间的介词的用法。既然第一句中用了long before,这里谈到原子裂变,将这个时间具体化,所以要说decades before,意思是原子裂变发现几十年之后才出现了该成果的应用。所以,惟有 B项符合题意。这个题也说明了做这类完形填空题中上下文相互参照的重要性。
转载请注明原文地址:https://kaotiyun.com/show/LE6K777K
0
专业英语四级
相关试题推荐
FormanyyearsitwascommonintheUnitedStatestoassociateChineseAmericanswithrestaurantsandlaundries.Peopledidnot
A、Tomakereadingandmaththemostemphasizedsubjects.B、Toincludemorecourses,suchastechnologyandforeignlanguages.C、
A、Peopledonotfeelabigdeal.B、Peoplefeelcompletelyoccupied.C、Peoplefeelshockedandhurt.D、Peoplefeelangryandexas
Childrentodayspendmoretimestareatcomputer【S1】______andTVscreensbothatschoolandathome.Scientific【S2】______
Childrentodayspendmoretimestareatcomputer【S1】______andTVscreensbothatschoolandathome.Scientific【S2】______
PASSAGEFOURWhydoestheauthorsaythathiscarbecomestheextensionofhispersonality?
IntheInformationAge,themassmediahavebeenplayinganevermoreimportantroleinshapingoursociety.Inthefollowingex
Singles’Dayhasbeenhailedasanothervictorybymodernsocietyintermsofcommercialism.Businessmenviewitasagoldmine
PASSAGETHREEWhatisthepurposeofthispassage?
A、BSc.B、MBA.C、Ph.D.D、LLD.D需用排除法解答。关于学位授予体系,访谈一开始提到“firstdegree”,如BA或BSc;接下来提到Masterdegree,如MA、MSc或MBA;后来又提到Doctordegree
随机试题
分かる独居老人の気持ち青天のへきれきというか、思ってもみなかった一人暮らしを余儀なくされている。地方に単身赴任して生活した経験もないではないが、出勤途上に連れ合いを近くの病院に見舞い、仕事の都合がつけば帰途も立ち寄って、夜半から明朝まで
患者,女,25岁。月经初潮迟至,婚后日久不孕,耳鸣,手足心热,心烦少寐,便秘溲黄;舌红少苔,脉细数。激素测定:促黄体生成素35.6IU/L,卵泡刺激素10.2IU/L,睾酮4.9nmol/L。彩超:右侧卵巢大小为3.3cm×3.2cm。其内可探及18~22
A.血行转移 B.直接蔓延 C.淋巴转移 D.种植转移 E.神经转移小肠肉瘤转移到肋骨是
商业银行应针对理财顾问服务和综合理财服务的不同特点,分别制定理财顾问服务和综合理财服务的管理规章制度。()
1992年,以家电研发、生产和销售为主业的信达公司确立了“技术立企”的发展战略。公司董事长程静强调:“那些只引进不研发、落伍了再引进的企业,没有追求,必死无疑”。信达公司拒绝参与彩电行业价格战,每年将销售收入的5%投入研发。信达公司实行奖金与开发成果挂钩的
咏史诗是指以历史题材为咏写对象的诗歌创作。根据上述定义,下列诗歌属于咏史诗的是()。
下面说法正确的是()。
对SheetA工作表内的数据清单的内容,按主要关键字“年度”的降序次序和次要关键字“房租(万元)”的降序次序进行排序。完成对各年度房租、水电的分类汇总,汇总结果显示在数据下方,工作表名不变,保存EXC.XLSX工作簿。
Nowadaysmoreandmorepeoplerelyoncomputersorcellphonestocommunicate.Ithasthereforebecomeveryeasyforthemtofor
Wecommonlythinkofsportsmanshipinconnectionwithathleticcontests,butitalsoappliestoindividualoutdoorsports.Note
最新回复
(
0
)