| 听下面一段材料，回答第1-4题。 |
| 1. What is a blood transfusion? |
| A. Losing a lot of blood in a serious accident or a difficult operation. B. Finding out the amount of blood a patient needs for an operation. C. Taking blood from someone else and putting it into a patient's body. |
| 2. What finally made almost every blood transfusion successful? |
| A. The discovery of blood types. B. The founding of a blood bank. C. The experiment with sheep blood. |
| 3. According to the speaker, if you give 10% of your blood,how long does it take your body to replace it? |
| A. One week. B. Five days. C. One day. |
| 4. What is the main purpose of the speech? |
| A. To call on people to give blood. B. To explain what a blood transfusion is. C. To review the history of the research on blood. |