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
Canals are watercourses constructed to improve and extend natural waterways. They are generally built to facilitate transportati
Canals are watercourses constructed to improve and extend natural waterways. They are generally built to facilitate transportati
admin
2009-02-10
50
问题
Canals are watercourses constructed to improve and extend natural waterways. They are generally built to facilitate transportation, but from the beginning they have been used for many additional purposes including draining swamps, irrigating land for cultivation, and promoting economic development.
Canals are often classified by the size of vessel they can accommodate. Some small local canals, which are able to float only 100 to 300 ton boats or small rafts of timber, may be only 3 feet deep. Major barge canals generally range from 6 to 9 feet in depth, and some are as much as 10 or 12 feet deep. These canals can carry 1,350 to 2,000 ton craft. Ship canals are 25 feet or more deep and are capable of accommodating large vessels in the seagoing class.
Canals may also be classified as either water level or lock canals. Water level canals do not vary in height along their courses. The best known of these is the Suez Canal, which is at sea level. Lock canals, which include most modem waterways, contain locks, or special devices for raising and lowering boats along their courses by changing the depth of the water. Each lock is a stretch of water enclosed by gates at each end. After a boat enters the lock, water is let or drained out until it reaches approximately the same level as the water ahead.
What is the purpose of a canal lock?
选项
A、To keep out boats that are too large for the canal.
B、To measure the tonnage of canal boats.
C、To load and unload the cargo.
D、To change the depth of the watch
答案
D
解析
最后一段详细论述lock canal,指出这种运河的用处是改变水位方便船只通过。
转载请注明原文地址:https://kaotiyun.com/show/jE6K777K
0
专业英语四级
相关试题推荐
FormanyyearsitwascommonintheUnitedStatestoassociateChineseAmericanswithrestaurantsandlaundries.Peopledidnot
BenjieGoodheartisinhislate30s,adoreshispartnerandhasayoungson.Butthethoughtofmarriagehasparalyzedhimwith
Recently,afour-day/10-hour-per-dayhasbeenpromotedbyemployersasawaytocutcosts,conserveenergyandbuildamoreprod
Theabilitytocommunicateistheprimaryfactorthatdistinguisheshumanbeingsfromanimals.Anditistheabilitytocommunic
FourreasonsthatrosyNovemberjobsreportwasevenbetterthanitseemed.It’simportantnottomaketoomuchoutofasingle
ChristianshavegenerallyregardedChristmasasbothaholydayandholiday.【M1】______Customsofalllandshavebeenaddedup
A、Itisaninbornnature.B、Itcanhardlybetaught.C、Itcanbegreatlyimproved.D、Itishard-wired.C
ThefollowingtwoexcerptsareaboutthepracticeofrentingboyfriendsandgirlfriendsfortheChineseNewYear.Fromtheexcer
Imagineaworldinwhichtherewassuddenlynoemotion--aworldinwhichhumanbeingscouldfeelnoloveorhappiness,noterror
随机试题
插接后的钢丝绳强度相当于原钢丝绳的()。
3.辩证联系的含义是()。
10个月小儿,1月来咳嗽,发热,呼吸促,1周来嗜睡,进食差,间断呕吐,来急诊。查体体温38.9℃,嗜睡,营养差,前囟膨隆,颈抵抗(±)。脑脊液白细胞50×106/L(50/mm3),多核65%,单核35%,糖、氯化物降低,PPD试验(—)。可能为下列哪
代谢性酸中毒会导致动物
建筑高度超过100m的高层建筑,其生活给水系统宜采用的给水方式为()。
按照现行增值税制度规定,下列行为不应按“视同销售”征收增值税的有()。
现金的周转过程主要包括()。
()情况下旅馆不可以拒绝客人入住。
领导的实质是一个行政组织系统。
有一批节能有毒灯泡需要组织回收,领导让你负责,你如何开展这项工作?
最新回复
(
0
)