Any four of the following five features will be considered correct： arbitrariness, creativity ( productivity) ,duality (double articulation) displacement ,cultural transmission.
Arbitrariness: human language is arbitrary,i. e. there is no logical connection between a linguistic sign and what it refers to.
Productivity: Human language allows human beings to produce and understand an unlimited number of sentences they have never heard before. Animals have a limited number of signals for communication.
Duality: Human language is structured as having two levels. On the lower level there exist a limited number of sounds which are by themselves meaningless； on the higher level, there are an unlimited number of sound combinations. This feature gives human language great expressive power. Such a feature is totally lacking in any animal communication system.
Displacement: Humans with their language can talk about anything without being limited by time or space. But animal communication is limited to the "here" and "now" .
Cultural transmission: Human language is not genetically transmitted,but is taught and learnt.
Means of animal communication is genetically transmitted.
答出以下五个功能中的四个功能即可：任意性，创造性(多产性)，二元性(两重性)、位移性、文化传递性。
任意性:人类语言是任意性的。语言符号和它所指的事物之间没有逻辑联系。
多产性:人类语言可以让人类产生和理解无数他们从未听过的句子。而动物的交流信号数量却是有限。
二元性:人类语言有两个层次。在低水平存在有限数量的声音本身毫无意义;在更高层面上,有无限的声音组合。这一特性赋予人类语言强大的表达能力。这样的特征在任何动物的交流系统中都是完全缺乏的。
位移性:人类用他们的语言可以谈论任何事情而不受时间或空间的限制。但动物之间的交流仅限于“此时此地”。
文化传递性:人类语言不是遗传的，而是被教授和学习的。动物的交流方式是通过基因遗传的。
