According to the first paragraph, pictures of animals were painted on the walls of caves because ______.
A. the pictures were thought to be helpful
B. the painters wanted to tell stories in pictures
C. the painters wanted to paint their hunted animals
D. both A and B
400名肥胖患者用气功疗法减肥，随访半年，60%的人体重降至正常。对此项研究，你的结论是
A. 气功疗法减肥效果好，观察半年 60%的病人有效
B. 此法效果可疑，40%未见效
C. 无法做出结论，因样本较小
D. 无法做出结论，因未设对照组
E. 无法做出结论，因未进行统计学检验
具有传染性，发丘疹损害的皮肤病称为
A. 疥
B. 湿毒
C. 丘疹
D. 癣
E. 湿疹
Dr. Leakey studied chimpanzees in Africa because（）
A. he thought that they were the best friends of humans'
B. he believed that prehistoric people might live a life similar to the life chimps lived now
C. he loved the animals
D. the chimpanzees were very shy
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