首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
The idea of a fish being able to produce electricity strong enough to light lamp bulbs—or even to nm a small electric motor—is a
The idea of a fish being able to produce electricity strong enough to light lamp bulbs—or even to nm a small electric motor—is a
admin
2009-06-24
45
问题
The idea of a fish being able to produce electricity strong enough to light lamp bulbs—or even to nm a small electric motor—is almost unbelievable, but several kinds of fish are able to do this. Even more strangely, this curious power has been acquired in different ways by fish belonging to very different families.
Perhaps the most known are the electric rays, or torpedoes, of which several kinds live in warm seas. They possess on each side of the head, behind the eyes, a large organ consisting of a number of hexagonal-shaped cells rather like a honeycomb. The cells are filled with a jelly-like substance, and contain a series of flat electric plates. One side, the negative side, of each plate, is supplied with very fine nerves, connected with a main nerve coming form a special part of the brain. Current gets through from the upper, positive side of the organ downward to the negative, lower side. Generally it is necessary to touch the fish in two places, completing the circuit, in order to receive a shock.
The strength of this shock depends on the size of fish, but newly-born ones only about 5 centimeters across can be made to light the bulb of a pocket flashlight for a few moments, while a fully grown torpedo gives a shock capable of knocking a man down, and, if suitable wires are connected, will operate a small electric motor for several minutes.
Another famous example is the electric eel. This fish gives an even mere powerful shock. The system is different from that of the torpedo in that the electric plates run longitudinally and are supplied with nerves from the spinal cord. Consequently, the current passes along the fish from head to tail. The electric organs of these fish are really altered muscles and like all muscles are apt to tire, so they are not able to generate electricity for very long. People in some parts of South America who value the electric eel as food, take advantage of this fact by driving horses into the water against which the fish discharge their electricity. The horses are less affected than a man would be, and when the electric eels have exhausted themselves, they can be caught without danger.
The electric catfish of the Nile and of other African fresh waters has a different system again by which current passes over the whole body from the tail to the head. The shock given by this arrangement is not so strong as the other two, but is none the less unpleasant. The electric catfish is a slow, lazy fish, fond of glooray places and grows to about 1 metre long; it is eaten by the Arabs in some areas.
The power of producing electricity may serve these fish both for defence and attack. If a large enemy attacks, the shock will drive it away; but it appears that the catfish and the electric eel use their current most often against smaller fish, stunning them so that they can easily be overpowered.
选项
A、The electric eel.
B、The electric catfish.
C、The newly-born electric torpedoes.
D、The fully-grown electric ray.
答案
A
解析
转载请注明原文地址:https://kaotiyun.com/show/SPTd777K
本试题收录于:
公共英语五级笔试题库公共英语(PETS)分类
0
公共英语五级笔试
公共英语(PETS)
相关试题推荐
Accordingtothepassage,whichofthefollowinghaschangedthemostinthelast500years?Whichofthefollowingstatements
A.Ford’sopponentsB.TheassemblylineC.Ford’sgreatdreamD.TheestablishmentofthecompanyE.Ford’sbiggestcontrib
A.Ford’sopponentsB.TheassemblylineC.Ford’sgreatdreamD.TheestablishmentofthecompanyE.Ford’sbiggestcontrib
Ford1Ford’sgreatstrengthwasthemanufacturingprocess—notinvention.Longbeforehestartedacarcompany,hewasaworker
WeconsumealotmorethanweareabletoProduce.
WeallknowthatSharonisawomanofstrongpoliticalconvictions.
Thetestproduceddisappointingresults.
AoccursmostinfrequentlyBisshiftedsidewaysbystrongwindsCisoftenhiddenfromourviewDisequippedwithagoodknowl
Theframeneedstobestrongenoughtosupporttheengine.
APayRiseorNot?"UnlessIgetarise.I’11haveatalkwiththeboss,HenryManley,"GeorgeStrongsaidtohimself.George
随机试题
将0.150g铁粉加入到20.0mL0.1mol/L的硫酸铜溶液中,充分反应后,溶液中含有哪些金属离子?它的物质的量浓度是多少?
杂志这种招募形式的优点有()
治疗阿米巴肝脓肿的首选药物
外阴瘙痒,查体双侧大阴唇皮肤可见对称性苔藓样变。可能为下列何项
案例九:甲企业向乙企业买了一批货物,约定由乙企业负责运送,甲企业负责对货物投保,甲企业根据约定与某保险公司签订了保险合同。根据案例九,回答下列问题:如果甲企业与保险公司订立合同后,又与另一保险公司就货物同样的保险事故和保险事项订立了保险合同,并且两个
【资料】在学《谁是最可爱的人》时,教师问:“谁是最可爱的人呢?”一个学生站起来说:“老师,我是不是最可爱的人啊?”老师说:“你热爱劳动,乐于助人,你是可爱的人;如果你能按时完成作业,认真听讲,上课积极发言,那么你就是最可爱的人。”你认为教师在对学生实施
玻璃幕墙的光反射并不能造成光污染。()
threatensforhealthierA.agovernmentwithfiniteresourcesshouldsimplystoppaying【T7】______medicalcareB.ourfailure
依据我国法律的规定,引起债消灭的原因包括( )。
坚持一个中国原则的内涵有()
最新回复
(
0
)