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
By the 1820’s in the United States, when steamboats were common on western waters, these boats were mostly powered by engines bu
By the 1820’s in the United States, when steamboats were common on western waters, these boats were mostly powered by engines bu
admin
2010-07-06
39
问题
By the 1820’s in the United States, when steamboats were common on western waters, these boats were mostly powered by engines built in the West (Pittsburgh, Cincinnati, or Louisville), and of a distinctive western design specially suited to western needs. The first steam engines 【21】______ practical use in England and the United States were 【22】______ low-pressure design. This was the type first 【23】______ by James Watt, then manufactured by the firm of Boulton and Watt. Steam was 【24】______ in a large, double-acting vertical cylinder, but the steam reached only a few pounds of pressure per square inch. It was low-pressure engines of this type that 【25】______ first introduced into the United States by Robert Fulton. He 【26】______ such a Boulton and Watt engine from England to run the Clermont. But this type of engine was ,expensive and complicated, 【27】______ many precision-fitted moving parts.
The engine that became standard on western steamboats was of a different and 【28】______ design. It was the work primarily of an unsung hero of American industrial progress, Oliver Evans (1755-1819), the 【29】______ son of a Delaware farmer. Evans early became 【30】______ by the possibilities of mechanized production and steam power. As early as 1802 he 【31】______ a stationary steam engine of high-pressure design in his mill. Engines of this type were not 【32】______ , but before Evans they were generally considered 【33】______ and dangerous. Within a decade the high-pressure engine, the new type, had become standard on western waters. Critics 【34】______ of western conditions often attacked it as wasteful and dangerous.
But people who really knew the Ohio, the Missouri, and the Mississippi 【35】______ , with good reasons, that it was the only engine for them. In 【36】______ western rivers the weight of vessel and engine 【37】______ important; a heavy engine added to the problem of navigation. The high-pressure engine was 【38】______ lighter in proportion to horsepower, and, with less than half as many moving parts, was much easier and cheaper to repair. The main advantages of low-pressure engines were safe operation and 【39】______ of fuel consumption, 【40】______ of which meant much in the West..
【32】
选项
A、known
B、knowing
C、unknowing
D、unknown
答案
D
解析
转载请注明原文地址:https://kaotiyun.com/show/PHDd777K
本试题收录于:
公共英语四级笔试题库公共英语(PETS)分类
0
公共英语四级笔试
公共英语(PETS)
相关试题推荐
RecentsurveysshowthatJapaneseyouthhavebecomea"MeGeneration"thatrejectstraditionalvalues."Around1980manyJap
A=BOOK1B=BOOK2C=BOOK3D=BOOK4Whichbook(s)say(s)that...theclimateaffectsthefuturesustainableagricultural
A=BOOK1B=BOOK2C=BOOK3D=BOOK4Whichbook(s)say(s)that...theclimateaffectsthefuturesustainableagricultural
Inrecentyears,therehasbeenanincreasingawarenessoftheinadequaciesofthejudicialsystemintheUnitedStates.Costsa
Youhavereadanarticleinamagazinewhichstates,"Withtheever-increasinghousepricesinbigmetropolises,itisbetterf
Whichpassage(s)say(s)that….adultsputtoomuchemphasisonchildren’sintellectualdevelopment?
TheissueofonlineprivacyintheInternetagefoundnewurgencyfollowingtheSept.11terroristattacks,sparkingdebateover
Whatdoesthespeakersuggestthatthestudentsshoulddoduringtheterm?
HowdoesAusubelfeelaboutthescientificprogressmadeeveryday?Technologicalprogresscanbedescribedasaprocessoftec
随机试题
男性,20岁,一直服用抗高血压药物2年,效果不佳,血压200/110mmHg,左上腹可听到血管杂音,为确诊高血压的原因,最有价值的检查是
妊娠期龈炎的临床变化与血中哪项激素水平相一致
药物按一级动力学消除具有以下哪些特点
社会技术支持的管理、松散的专家网络系统在时间上与专家质量上难以保证项目需要。在建立专家系统时准备工作包括(),建立计算机管理系统资料入库,并委派专人进行管理。
流动性风险监测指标中,()反映了银行存款的集中度。
材料:(1)某学生在教师上完同分异构体一课后,向教师提出了一个很简单的问题:一氯甲烷有没有存在同分异构体?师答:没有。生:哦,我知道了。(2)第二天该学生又拿了一个相似的问题来请教:二氯甲烷是否存在同分异构体呢?师反
以下不属于同类班级规章制度的是()。
思维是一个复杂的认识过程,思维的操作过程包括()
(x2+1)(x一2)7的展开式中x3项的系数是().
A、Bobhasalsobeenmadatherrecently.B、ThemanshouldaskBobtoapologize.C、Bobmightnotbereallyangrywiththeman.D、
最新回复
(
0
)