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、Gas produced by metal and coal. B、Air kept hot by burning coal. C、Hydrogen heated by a gas burner. D、Natural gas carried in a
A、Gas produced by metal and coal. B、Air kept hot by burning coal. C、Hydrogen heated by a gas burner. D、Natural gas carried in a
admin
2009-03-21
53
问题
Balloons consist of a large flexible bag containing either hot-air or the gas that is lighter than air. The bag no neither envelope is made of silk, rubber or other suitable materials. Piloted balloons carry one or more persons; unpiloted balloons are usually used for scientific research and carry instruments to measure and record a variety of physical phenomena. Since the first successful manned balloon flied in 1783, hot-air balloons have been flown primarily for pleasure. Although the military made extensive use of them in World War I, occasionally rised for sport, the colorful globes are a more commonly thing flying in the sky during the summer when visibility is high and the flights are generally peaceful. Any gas that is lighter than air can be used to lift the balloon. Natural gas, heated air and manufactured gas can and have been used to fly balloons. The earliest balloons were filled with hot-air and often carried a metal container for burning coal to continuously heat the air. Modern balloons are usually filled with hydrogen or air heated by a small gas burner. Balloons are used primarily for two purposes, sport or scientific research. Sport balloons mostly use hot-air, they range from 10 to 20 meters in size when the bag’s inflated; scientific balloons generally use hydrogen and some particular gases. They range in size from 30 to 200 meters when fully inflated.
Questions:
11. The common use of unpiloted balloons is______
12. Why do people usually fly hot-air balloons in summer?
13. What enabled the earliest balloons to fly?
选项
A、Gas produced by metal and coal.
B、Air kept hot by burning coal.
C、Hydrogen heated by a gas burner.
D、Natural gas carried in a metal container.
答案
B
解析
转载请注明原文地址:https://kaotiyun.com/show/08Pd777K
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
Inathree-monthperiodlastyear,twoBrooklyniteshadtobecutoutoftheirapartmentsandcarriedtohospitalonstretchers
"Themoregadgetsthereare,the【31】______thingsseemtoget."saidHonoreErvin,co-authorofTheEtiquetteGirls:ThingsYou
Earthquakescanbedevastating【1】disasters.TheinfamousSanFranciscoearthquakeof1906causedover$200millionworthofdam
AnswerQuestions71to80byreferringtothefollowingfourarticlesconcerningmentalillness.Answereachquestionbychoosin
PaoloFril,chairmanandscientificofficerofGeneDupe,basedinSanMelito,California,isamanwithadream.Thedreamisa
Artwasherfavoritesubjectatschool,butshedidadegreeingeography.
Academic
UNSecretary-GeneralKofiAnnanvisitedthetroubledDarfurregionofwesternSudanThursdaytoconsiderwaystoendthehumanit
UNSecretary-GeneralKofiAnnanvisitedthetroubledDarfurregionofwesternSudanThursdaytoconsiderwaystoendthehumanit
Friday本题答案信息也是隐含在最后一个话轮男士的最后一句中:...orjustcomehereonthenextmorningtogettheresult。这一题与上一题的听音和答题紧密相关,因为前面说的是Thursday(星期
随机试题
在计算机中,运算器的作用是进行______。
Hewasdefeatedinthecompetitionpartlybecausehewas______tothefeelingsofothers.(sense)
慢性风湿性瓣膜病常见的联合瓣膜损害是
治疗心室扑动,下述措施中最有效的是()
彩色透明软片和纸基像片应在()的条件下,对其进行快速干燥。
2013年4月10日,甲施工单位职工王某因参与打架斗殴被判处有期徒刑1年,缓期3年执行,2013年5月1日,甲施工单位经过研究决定解除与王某的劳动合同。但考虑到王某在单位工作多年,决定向其多支付1个月的额外工资,随后书面通知了王某。这种劳动合同解除的方式称
三相异步电动机的转子有()。
公司信贷风险预警的理论和方法主要包括()。
利用图片、图表、模型、幻灯片、电影电视等手段进行教学的直观类型是()。
根据反不正当竞争法的相关规定,经营者进行抽奖式的有奖销售,最高奖的金额不得超过三万元。()
最新回复
(
0
)