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
2024-10-14
15
管理
问题
What does the passage mainly discuss?
Canals are watercourses constructed to improve and extend natural waterways. (11) 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.
(11) 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. (13) 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. (12) 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:https://tihaiku.com/zcyy/3800600.html
相关试题推荐
Beforediscussingtheeffectofdeflationandinflationonthedistribution
Beforediscussingtheeffectofdeflationandinflationonthedistribution
Beforediscussingtheeffectofdeflationandinflationonthedistribution
Beforediscussingtheeffectofdeflationandinflationonthedistribution
Beforediscussingtheeffectofdeflationandinflationonthedistribution
Beforediscussingtheeffectofdeflationandinflationonthedistribution
Beforediscussingtheeffectofdeflationandinflationonthedistribution
Beforediscussingtheeffectofdeflationandinflationonthedistribution
Beforediscussingtheeffectofdeflationandinflationonthedistribution
Beforediscussingtheeffectofdeflationandinflationonthedistribution
随机试题
EARTH’SENERGYCYCLE(1)To
减灾救灾disasterreductionandrescue
EndangeredPeoplesA)Today,itisnotdistance,butculturethatseparate
[originaltext]Manyayoungpersontellsmehewantstobeawriter.Ialwaysen
锚杆、锚碇板和加筋土挡土墙墙背填土的实测项目的关键项目是()。A.锚杆间距
患儿,3岁,饮食异常,精神烦躁,睡眠不安,肛门、会阴部瘙痒。诊断为A.钩虫病
柴胡可以A.养益肝阴B.平肝潜阳C.疏肝破气D.疏肝解郁E.柔肝止痛
应由执业药师指导购买、销售和使用的药品是A.甲类非处方药B.乙类非处方药C.口服
当其他影响血压的因素不变时,下列哪些因素可引起脉压增高?( )A.每搏量增加
社会主义市场经济体制的基础是( )。A、以间接手段为主的完善宏观调控体系 B、
最新回复
(
0
)