题目内容：
Directions : There are 2 0 blanks in the following passage . For each blank there are four choices narked A ) , B ) , C ) and D ) on the right side of the paper . You should choose the ONE that best fits into the passage . Then mark the corresponding letter on the Answer Sheet with a single line through the center . A language is a signaling system which operates wi th synbolic vocal sounds ) and vhich is used by a graup of people for the purpose of connunication .
Let . s look at this 1 innore detail because it is language , nore than anything else , 2 distinguishes nan from the rest of the 3 world . Other aninals , it is true , comnunicate with one another by 4 of cries : for exanple , nany birds utter 5 calls at the approach of danger ; nonkeys ut ter 6 cries , such as expressions of anger , fear and pleasure . 7 these various means of di ffer in important ways 8 hnan language .
For ins tance , animals . cries do not 9 thoughts and feelings clearly . This neans , basically , that they lack structure . They lack the kind of structure that 1 0 us to divide a human utterance into 1 1 .
Ve can change an ut terance by 1 2 one vord in it with 1 3 : a good illustration of this is a soldier who can say , e . g . , " tanks approaching from the north " , 1 4 who can change one word and say " aircraft approaching from the north " or " tanks approaching fron the west " , but a b
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