【正确答案】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 mumber 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．