For a long time, people thought that the floor of the ocean was a very quiet place. Some thought that it was almost without any s{#blank#}1{#/blank#} at all. Scientists were surprised when they put a microphone (麦克风) under water and heard all kinds of noises. They heard grunts, growls, snarls and whistles. The b{#blank#}2{#/blank#} of the sea sounded like a zoo! The scientists were puzzled (迷惑的) when they found out these noises were c{#blank#}3{#/blank#} from fish. Some fish make noise by grinding their teeth. Others scrape their bones together. Still others make noise with the sac of air in their bodies. W{#blank#}4{#/blank#} fish make these sounds is somewhat a mystery (谜). Some scientists think that the fish use these noises to s{#blank#}5{#/blank#} to one another. Most people believe the sounds have no meaning. Scientists have found out that the dolphin k{#blank#}6{#/blank#} the meaning of some sounds. Tests show that it is one of the smartest a{#blank#}7{#/blank#} in the sea. People say that they have been able to teach the dolphin many human words. At Marineland of the Pacific, it is said that dolphins have even been taught to sing. They rise to the s{#blank#}8{#/blank#} of the water and sing for visitors. At least it sounds somewhat like singing!

    Who knows? We may be able to talk with the dolphin and learn many secrets of the sea sometime soon. Just think what the dolphin could tell us. We could learn the location of treasure ships u{#blank#}9{#/blank#} the sea. We could learn where to find great schools of fish. We might e{#blank#}10{#/blank#}learn the location of submarines (潜艇). It could be an exciting moment when we first begin to find out what those voices from the ocean floor are saying.