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The idea of a fish being able to generate electricity strong enough to light lamp bulbs--or even to run 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 best known are the electric rays, or torpedoes(电鳐), 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 from a special part of the brain. Current passes from the upper, positive side of the organ downwards, 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 the fish, but newly born ones only about 5 centime-tres 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 more powerful shock. The system is different from that of the torpedo in that the electric plates run longitudinally(纵向) and are supplied with nerves from the spinal(脊骨) 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 (likely) to tire, so they are not able to produce electricity for very long. The power of producing electricity may serve these fish both for defense and attack. The reason why the electric eel is able to give more powerful shock is that______.

A.
the working system of the electric plates in the eel is the most effective
B.
the working system of the electric plates in the eel is far inferior to those in the torpedo
C.
compared with those in the torpedo, the working system of electric plates in the eel is more direct and efficient
D.
compared with other electric fish, the eel possesses much more electric plates
题目标签:电鳐
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【单选题】The idea of a fish being able to generate electricity strong enough to light lamp bulbs--or even to run a small electricmotor-is almost unbelievable, but several kinds of fish are able to do this. Eve...

A.
a mature torpedo is capable of producing enough electricity to knock down a man
B.
the mass of the fish decides the intensity of electric power it generates
C.
the strength of shock given by a young electric ray can only light the bulb of a pocket flashlight
D.
to make full use of the energy produced by electric fish, suitable wires should be available

【单选题】Part A Directions: Read the following three texts. Answer the questions on each text by choosing A, B, C or D. Mark your answers on ANSWER SHEET 1. The idea of a fish being able to generate electricit...

A.
the capacity to generate electricity is the distinctive characteristic of the fish
B.
the current travels in an upward direction from the positive side to negative side in torpedo's electric cells
C.
some fish can produce enough electricity to drive a number of electricmotors
D.
the torpedo's electric cells have a shape with six sides

【单选题】The idea of a fish being able to generate electricity strong enough to light lamp bulbs--or even to run a small electric motor--is almost unbelievable, but several kinds of fish are able to do this. E...

A.
a mature torpedo is capable of producing enough electricity to knock down a man
B.
the mass of the fish decides the intensity of electric power it generates
C.
the strength of shock given by a young electric ray can only light the bulb of a pocket flashlight
D.
to make full use of the energy produced by electric fish, suitable wires should be available

【单选题】The idea of a fish being able to generate electricity strong enough to light lamp bulbs— or even to run a small electricmotor— is almost unbelievable, but several kinds of fish are able to do this. Ev...

A.
the capacity to generate electricity is the distinctive characteristic of the fish
B.
the current travels in an upward direction from the positive side to negative side in torpedo"s electric cells
C.
some fish can produce enough electricity to drive a number of electricmotors
D.
the torpedo"s electric cells have a shape with six sides

【单选题】Text 1 The idea of a fish being able to generate electricity strong enough to light lamp bulbs--or even to run a small electricmotor-is almost unbelievable, but several kinds of fish are...

A.
the current in one place is not strong enough to give a shock
B.
the fish’s electric cells are filled with jelly like substance
C.
to complete the circuit, you have to touch the fish in two places
D.
a torpedo’s electric cells contain more than one electric plates

【单选题】The idea of a fish being able to generate electricity strong enough to light lamp bulbs--or even to run a small electric motor--is almost unbelievable, but several kinds of fish are able to do this. E...

A.
the working system of the electric plates in the eel is the most effective
B.
the working system of the electric plates in the eel is far inferior to those in the torpedo
C.
compared with those in the torpedo, the working system of electric plates in the eel is more direct and efficient
D.
compared with other electric fish, the eel possesses much more electric plates

【单选题】The idea of a fish being able to generate electricity strong enough to light lamp bulbs--or even to run a small electric motor--is almost unbelievable, but several kinds of fish are able to do this. E...

A.
the current in one place is not strong enough to give a shock
B.
the fish’’ s electric cells are filled with jelly-like substance
C.
to complete the circuit, you have to touch the fish in two places
D.
a torpedo’’ s electric cells contain more than one electric plates