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
2023-11-22
77
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 does the passage mainly discuss?
选项
A、How canals are constructed.
B、Common types of canal boats and barges.
C、The world’ s largest canals.
D、How canals are used and classified.
答案
D
解析
通读全文不难发现,每段第一句即为段落主题句,第一段讲什么是canal,第二、三段讲的canal不同分类及其作用,因而本题应该选D。
转载请注明原文地址:https://tihaiku.com/zcyy/3210710.html
相关试题推荐
PASSAGEONE[br]Towhichdirectiondothethornsextendtheirbranchesaccordin
我们大家都必须不断充电提高自己。Weallmustconstantlyrenewourknowledgesoastoimproveours
Itisnaturaltofeeluncomfortableinalanguageclass.You’reusedtobeing
Itisnaturaltofeeluncomfortableinalanguageclass.You’reusedtobeing
Itisnaturaltofeeluncomfortableinalanguageclass.You’reusedtobeing
Itisnaturaltofeeluncomfortableinalanguageclass.You’reusedtobeing
Itisnaturaltofeeluncomfortableinalanguageclass.You’reusedtobeing
Itisnaturaltofeeluncomfortableinalanguageclass.You’reusedtobeing
Itisnaturaltofeeluncomfortableinalanguageclass.You’reusedtobeing
PassageOne[br]SelectandwritedownatleastFOURnaturalobjectstheTim
随机试题
A:Excuseme,areyouMr.Road?B:______.A、I’mnotB、SorryC、Yes,IamC此题考查情景英
Salesdidn’tchangefrom1998to2000.[br]Salesfellon1999androseagainto
Ithasbeenprovedallofthefollowingexceptthat______.[br]Theunderlined
[originaltext]M:Ifyouhadsignaledyourintentiontoturnalittlesooner,th
"Hightech"and"stateoftheart"aretwoexpressionsthatdescribeverymo
民航运输业存在着规模经济特征,随着总运辅量的不断变化。干平均总成本曲线()
针对顺查法,以下说法正确的有()。A.是指审计取证的顺序与反映经济业务的会
Thechangeinthatvillagewasmiraculou
关于承诺,下列说法错误的是()。A:承诺可以撤回B:承诺可以撤销C:承诺通知
作为金融中介机构,商业银行的经营对象是()A.内控和风除 B.信贷和风险 C
最新回复
(
0
)