A．He was sick.
B．His wife was sick.
C．His wife just had a baby.
D．He was visiting his daughter.

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