首页
登录
职称英语
As in the field of space travel, so in undersea exploration new technologies con
As in the field of space travel, so in undersea exploration new technologies con
游客
2023-07-18
42
管理
问题
As in the field of space travel, so in undersea exploration new technologies continue to appear. They share a number of similarities with each other—as well as some important differences.
Manned submersibles.(潜水器), like spaceships, must maintain living conditions in an unnatural environment. But while a spaceship must simply be sealed against the vacuum of space, a submersible must be able to bear extreme pressure if it is not to break up in deep water.
In exploring space, unmanned vehicles were employed before astronauts. In undersea exploration, on the other haled, men paved (铺路) the way, and only recently have unmanned remote-operated vehicles (ROVs) been put to use.
One reason for this is that communicating with vehicles in orbit is much easier than talking to those underwater. A vacuum is an ideal medium for radio communications, but underwater communications are limited to much slower sound waves. Thus, most undersea vehicles—particularly ROVs—operate. at the end of long process.
For a similar reason, knowing where you are undersea is much more difficult than in space. A spaceship’s position can be located by following its radio signal, or by using telescopes and radar. For an undersea vehicle, however, a special network of sonar (声纳) devices most be laid out in advance on the ocean floor in the area of a dive to locate the vehicle’s position.
Though undersea exploration is more challenging than outer space in a number of respects, it has a distinct advantage: Going to the ocean doesn’t require the power necessary to escape Earth’s gravity. Thus, it remains far less expensive. [br] By saying "more challenging" in the last paragraph the author means that undersea exploration is ______
选项
A、more interesting
B、more attractive
C、more demanding
D、more dangerous
答案
C
解析
此题考查根据上下文正确理解词义的能力, challenging意为“富有挑战性的”,与C)项中的demanding“要求高的,费力的”意思相近
转载请注明原文地址:https://tihaiku.com/zcyy/2848165.html
相关试题推荐
______(由于航空公司间激烈的竞争),travelexpenseshavebeenreducedconsiderably.Owingtofi
TipsforTravelingAloneWhenitcomestotraveling,so
TipsforTravelingAloneWhenitcomestotraveling,so
TipsforTravelingAloneWhenitcomestotraveling,so
TipsforTravelingAloneWhenitcomestotraveling,so
TipsforTravelingAloneWhenitcomestotraveling,so
FrequentbusinesstravelerJoyceGioiaforgotmorethan$20000worthofje
FrequentbusinesstravelerJoyceGioiaforgotmorethan$20000worthofje
FrequentbusinesstravelerJoyceGioiaforgotmorethan$20000worthofje
FrequentbusinesstravelerJoyceGioiaforgotmorethan$20000worthofje
随机试题
[originaltext]WhenareyouleavingforNewZealand?(A)Intwoweeks.(B)I’mv
•Lookatthenotebelow.•Youwillhearaman’sschedule.1Onmondayat(5)
Mostparentsprizethediversitywithintheirchildren’spublicschools.The
Touristsbecomeperplexedbecausetheydon’tknowstreetnamesarepostedonthe
[img]2014m9x/ct_egreqm_egreqbj_0056_20148[/img][br]CInthisquestion,youare
Nocountryshouldbeallowedto__________________(干涉其他国家的内部事务).interferewith/
A.四环素 B.氯霉素 C.链霉素 D.嘌呤霉素能与原核生物的核糖体大亚基
A.川芎、延胡索 B.没药、红花 C.益母草、牛膝 D.三棱、虻虫 E.
甲状腺功能亢进症病人不宜进食的食物是A.高脂食物 B.高蛋白质食物 C.高碘
对鼓膜传音功能不正确的叙述是A.在振动频率为16~20000Hz范围内,鼓膜振动
最新回复
(
0
)