A. function B. warning C. definition D. replacing E. express F. words G. deeds H. interpret I. limitless J. single K. boundless L. general M. ordinary N. distinguishes O. different 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 1 in more detail because it is language, more than anything else, that 2 man from the rest of the animal world. Other animals, it is true, communicate with one another by means of cries: for example, many birds utter 3 calls at the approach of danger, monkeys utter 4 cries, such as expressions of anger, fear and pleasure. But these various means of communication differ in important ways from human language. For instance, animals' cries do not 5 thoughts and feelings clearly. This means, basically, that they lack structure. They lack the kind of structure that enables us to divide a human utterance into 6. We can change an utterance by 7 one word in it with another: a good illustration of this is a soldier who can say, e.g., "tanks approaching from the north", and who can change one word and say "aircraft approaching from the north" or "tanks approaching from the west"; but a bird has a 8alarm cry, which means "danger! " This is why the number of signals that an animal can make is very limited: the great tit is a case in point; it has about twenty different calls, whereas in human language the number of possible utterances is 9. It also explains why animal cries are very 10 in meaning.