【正确答案】正确答案：Both the traffic light system and human linguistic system can symbolize some information in communication whereas the linguistic system is more complicated. However, the linguistic system has several distinctive features that no other systems have, including the traffic light system. (1) Language is arbitrary which means that there is no logical connection between meanings and sounds. But in traffic light system, there are direct logical connections between the light signals and their meanings. (2) Language is hierarchical, that's to say linguistic system has two levels of structures, such that units of the primary level are composed of elements of the secondary level and each of the two levels has its own principles of organization. However, the traffic light system has no hierarchical system and the structure is composed by a single level. (3) Language is creative. By creativity we mean language is resourceful because of its duality and its excursiveness. Because of duality, speaker is able to combine the basic linguistic units to form an infinite set of sentences, most of which are never before produced or heard. But there is no recursive nature in traffic light system which means that it can not produce new meaning.