[单项选择]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 be- longing to very different families.
Perhaps the best known are the electric rays, or torpedoes (电鱼), of which several kinds live in warm seas. They posses 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
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

[单项选择]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. 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,
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