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
68
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..
【25】
选项
A、is
B、was
C、are
D、were
答案
D
解析
转载请注明原文地址:https://kaotiyun.com/show/tHDd777K
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
Wheredidriceoriginate?
What’stheaverageincreaseperyearofforeignstudentpopulationintheperiodbetween1985and1990intermsofpercentage?
Whatarethespeakersdoing?
A=BOOK1B=BOOK2C=BOOK3D=BOOK4Whichbook(s)say(s)that...theclimateaffectsthefuturesustainableagricultural
A=BOOK1B=BOOK2C=BOOK3D=BOOK4Whichbook(s)say(s)that...theclimateaffectsthefuturesustainableagricultural
IfyouarebuyingapropertyinFrance,whetherforapermanentoraholidayhome,itisimportanttoopenaFrenchbankaccount
Youhavereadanarticleinamagazinewhichstates,"Bylaw,cigaretteadvertisementsarestrictlyprohibitedonthemedia.Som
HowdoesAusubelfeelaboutthescientificprogressmadeeveryday?Thespeaker’sfriendswerefuriousbecausetheirreportdid
In1935,MaryKaygotmarriedforthefirsttime.
IBMwasviewedbymostworkersas______.Fromthispassage,wecanconclude______.
随机试题
患者女,21岁。因面容不佳,开唇露齿要求治疗。按正畸正颌联合治疗的方案,人院前约2年已行相关的正畸治疗,已经将牙列排齐,现要求手术矫正。检查:患者口唇未能完全闭合,开唇露齿。∠SNA86.6°,∠SNB84.2°。后牙咬合正常,前牙有较好的覆颌覆盖,中线正
患者女,50岁。心悸气短,头晕目眩,活动后症状加重。近29来发热咳嗽,心悸喘促不能平卧,面唇发绀,呼吸困难,汗出,身肿而来急诊。检查:体温38.7℃,血压95/65mmHg,神识昏惑,面唇及指端发绀,两肺底湿性哆音,心尖部可听到3级双期杂音,心率128次
白喉、百口咳、破伤风混合疫苗初种时需
高位水箱用于贮水和稳定水压,水箱通常用( )等材料制作。
铁路简支梁主要采用()方法架设。
下列有关固定资产初始计量的表述中,正确的有()。
在房地产项目前期策划中,分析“建什么”是解决()问题。
按现行规定,在计算应纳税所得额时不得扣除的支出是()。
查明和确认测量仪器是否符合法定要求的程序,被称为()。
简述χ2检验的假设。
最新回复
(
0
)