Some animals that cannot see can still tell the difference between light and darkness, while others can react to chemicals, which is something like smelling and tasting. However, there may be a sense that we know nothing about, for otherwise it is very hard to explain how birds, animals and even insects and fish manage to travel long distances without losing their way.
Only man can tell his companions exactly what he wants, for he has the wonderful gift of speech; but many of the larger animals can show that they are hungry or frightened or pleased by making sounds that we have learned to recognize, such as a roar. Even man still uses animal-like sounds when he laughs or sighs.
Some animals can get further than these simple noises. For instance, a bird song is much more elaborate, for it tells other males to keep away, while at the same time inviting a female to come closer. Birds have other calls which warn of danger or help to keep the flock (鳥群) together. Of course, a parrot does not understand what it is saying when it imitates the human voice.
正確答案：一些沒有視覺的動物，仍能辨別出光線和黑暗的不同，而其它一些動物能對化學物質做出反應，就如同有味覺和嗅覺一樣。然而，一定存在一種我們不知道的感覺。因為如果不是這樣的話，就很難解釋為什么鳥、動物甚至昆蟲和魚能旅行很長的距離而不迷路。只有人能確切地告訴他的同伴他想要什么，因為人有奇妙的語言天賦，但是許多大一些的動物能夠發出我們已經學會辨別的聲音如吼叫來表達它們的饑餓、受驚或高興。甚至人類在笑或嘆息的時候仍然使用像動物的聲音。一些動物能發出比這些簡單的聲音更復雜的聲音，例如，鳥兒的歌聲就更復雜精細，因為它能告訴其它雄性鳥離開，同時邀請雌性鳥兒靠近。鳥兒有時發出聲音警告危險或使鳥群緊密結合。當然，當鸚鵡模仿人發聲的時候并不理解其中的含義。
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（責任編輯：中大編輯）
