首页
登录
职称英语
What does the passage mainly discuss? [originaltext] Canals are watercourses
What does the passage mainly discuss? [originaltext] Canals are watercourses
游客
2023-11-20
44
管理
问题
What does the passage mainly discuss?
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 modern 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.
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
转载请注明原文地址:http://tihaiku.com/zcyy/3204624.html
相关试题推荐
Whatisthemaintopicofthisconversation?[br][originaltext]M:Weseemtob
WhatdidHelenrecentlypass?[br][originaltext]M:Hi,Helen.Howdidyourdri
Whenistheguidedtourofthecampusgiven?[originaltext]M:I’mhereforthec
Howmanyoldpeoplehavebeenexaminedfortheresearch?[originaltext]Doct
WhichofthefollowingisNOTtrue,accordingtothepassageyouhavejustheard
WhichofthefollowingisNOTtrue,accordingtothepassageyouhavejustheard
Whatisthespeaker’sattitudetowardsheavymetalmusic?[br][originaltext]
Whatisthespeaker’sattitudetowardsheavymetalmusic?[br][originaltext]
Whatisthespeaker’sattitudetowardsheavymetalmusic?[originaltext]Mus
Thespeakeristalkingabout______.[br][originaltext]Fantasyisatough
随机试题
[img]2016m8s/ct_epekm_epelist_0322_201607[/img][br][originaltext]Mytelephone
Mr.Watsonaskedthestudentsto________theirhomework.A、handinB、fillinC、get
Smallcommunities,withtheirdistinctivecharacter—wherelifeis【C1】_______
FiveBadStudyHabitsIfyouhavepreparedforthetestsformanyhours,andyet
多段线(Pline)命令可以指定线宽。()
台港澳和华侨利用非开放档案,须经大陆邀请合作或接待单位介绍,提前30天向国家档案
下列关于国债招标方式发行中对于承销团成员承销额的限定,说法正确的是()。 ①
欧洲中世纪用于对普通贫民子弟传授宗教及读写知识的是()。
个体是否患有心理疾病,()。 (A)只有在心理咨询工作中被关心 (B)只有
下列货流中,按货物运输方向分类的货流是( )。A.过境货流 B.区间货流 C
最新回复
(
0
)