2002.10 阅读27 请问

Other behaviors that may indicate some cognition include tool use. Many  

(20)animals, like the otter who uses a stone to crack mussel shells, are capable of using  

objects in the natural environment as rudimentary tools. One researcher has found  

that mother chimpanzees occasionally show their young how to use tools to open  

hard nuts. In one study, chimpanzees compared two pairs of food wells containing  

chocolate chips. One pair might contain, say, five chips and three chips, the other  

(25)our chips and three chips. Allowed to choose which pair they wanted, the  

chimpanzees almost always chose the one with the higher total, showing some sort  

of summing ability. Other chimpanzees have learned to use numerals to label  

quantities of items and do simple sums.

27.  The word "rudimentary" in line 21 is closest in meaning to  

(A)  superior

(B)  original

(C)  basic

(D)  technical

答案改来改去 到底改选 B 还是 C 喃? 请说下理由啊

感觉太变态了

谢谢

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基本的．．．．