第28题: [单项选择]Questions 19 to 21 are based on the passage you have just heard. A. Because it is fun. B. Because they are forced to clean themselves. C. Because they’re proud of their pretty feathers. D. Because they have an instinct for cleanliness. 参考答案:D 答案解析:[解析] 19-21 Birds spend so much time smoothing, cleaning and arranging their feathers that it’
第29题: [单项选择]卫星现象中围绕神经元胞体周围的细胞是:() A. 少突胶质细胞 B. 星形胶质细胞 C. 小胶质细胞 D. 室管膜细胞 E. 小淋巴细胞 参考答案:A