听下面一段材料,回答第1至第3题。 1. What's the speaker mainly talking about? A. The history of blood donation. B. The purpose of blood donation. C. A general introduction of blood donation. 2. From whom can a hospital usually get the blood to save lives? A. Doctors. B. Patients. C. Healthy people. 3. How long will it take your body to make enough blood if you give blood? A. Several minutes. B. Only one day. C. About a week .