单项选择题

A language is a signaling system which operates with symbolic vocal sounds, and which is used by a group of people for the purpose of communication. Let’’s look at this 【B1】 in mom detail because it is language, more than anything else, 【B2】 distinguishes man from the rest of the 【B3】 world. Other animals, it is true, communicate with one another by 【B4】 of cries: for example, many birds utter 【B5】 calls at the approach of danger; monkeys utter 【B6】 cries, such as expressions of anger, fear and pleasure. 【B7】 these various means of communication differ in important ways 【B8】 human language. For instance, animals’’ cries do not 【B9】 thoughts and feelings dearly. This means basically that they lack structure. They lack the kind of structure that 【B10】 us to divide a human utterance into 【B11】 We can change an utterance 【B12】 one word in it with 【B13】 a good illustration of this is a soldier who can say, e.g., "tanks approaching from the north", 【B14】 who can change one word and say "aircraft approaching from the north" or "tanks approaching from the west"; but a bird has a single alarm cry, 【B15】　 means "danger!" This is why the number of 【B16】 that an animal can make is very limited: the great tit is a case 【B17】 point; it has about twenty different calls, 【B18】 in human language the number of possible utterances is 【B19】 It also explains why animal cries are very 【B50】 in meaning.