题目

A famous doctor once received a little child that was badly ill. Thanks to his skill and care, the child got well and was soon able to get up and run about again. The child’s mother was very thankful to the doctor, and she visited him for what he had done for her child. “Doctor,” she said, “you have saved my little son. I don’t know hoe to thank you enough. I feel that money alone cannot repay（回报）you, so I have made this little purse with my own hands, as a sign of my thanks. I hope you will accept（接受）it.” The doctor stood up and said coldly, “Madam, a little pres人类在生物圈中的立足点是（　　）A．水圈B．岩石圈表面C．大气圈D．生物圈任何地方