首页
登录
职称英语
Canals are watercourses constructed to improve and extend natural waterways
Canals are watercourses constructed to improve and extend natural waterways
游客
2024-10-31
27
管理
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. [br] 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://tihaiku.com/zcyy/3825279.html
相关试题推荐
Bycuttingdowntreeswe______thenaturalhabitatofbirdsandanimals.A、damag
Theredspotsfirstappearedontheforearmandthenextended______totheshou
AsIregardit,youcanwidenthe______oftheseimprovementsthroughyouracti
GermanhavelawmakersvotedtoextendandexpandtheroleofGermanpeacekeepers
GermanhavelawmakersvotedtoextendandexpandtheroleofGermanpeacekeepers
Canalsarewatercoursesconstructedtoimproveandextendnaturalwaterways
Thechairmanofthecompanysaidthatnewtechniqueshad__________improvedtheir
Ourape-menforefathershadnoobviousnaturalweaponsinthestruggleforsu
Ourape-menforefathershadnoobviousnaturalweaponsinthestruggleforsu
Ourape-menforefathershadnoobviousnaturalweaponsinthestruggleforsu
随机试题
Sartrebelievedeachindividualisresponsibletochooseonecourseofactionov
InWesternCulturesyoudon’topenacloseddoorwithoutknocking,unlessit
Thoseloggingcontractsmentionedinvolve______hectaresofforestinCongo.[o
Currentstudiesshowthatwhatgoesonlabelsisanimportantconsideration
[originaltext]W:Howhaveyourtwosonsbeendoingatschoollately,Andy?M:T
氧气雾化吸入,氧流量应调节为A.0.5L/min B.1~2L/min C.
1500ml的液体从早上8点半开始输,调节滴数为75滴/分,其输完的时间为A.1
两个运输队,第一队有320人,第二队有280人,现因任务变动,要求第二队的人数是
早在1985年,国务院就批准建立了产品质量国家监督抽查制度,并授权国家技术监督
某材料自甲、乙两地采购,相关信息如下表所示,则其材料单价为()元/t。A:63.
最新回复
(
0
)