阅读理解。 Many hospitals have blood banks. In these banks, blood of all types is stored. When blood is needed, it is taken from the bank. Healthy people then give blood to the bank to replace (取代) the blood that is used. Blood can be kept in the fridge for about three weeks with a kind of chemical. When people lose much of heir blood because of operation a accident, they may need transfusions (输血). Some people may need transfusions because of illness. Sometimes only a part of the blood is used for transfusions. Plasma (血浆), the liquid part of the blood, may be given alone. Transfusions of plasma are often given when people have been badly burned. When a person gets a transfusion, he gets blood of the same type as his. Or there may be a bad reaction (反应). To make it safer, before a transfusion is given, the blood to be used must be tested with the blood of the person who is to receive it. This testing is called cross matching of the blood. Oswald Robertson, an American doctor, was the first one to give transfusions. He used blood that had been stored for some time to help wounded soldiers in 1918 in World War I. 1. Blood banks usually have __________. A. only one type of blood B. one or two types of blood C. two or three types of blood D. all types of blood 2. Blood banks get blood from __________. A. healthy people B. operations C. accidents D. transfusions 3. Before a transfusion, it is important to make sure that __________. A. the blood is cold B. the blood has been stored long enough C. the blood is from people who have accidents D. the type of blood to be used is the same as the patient's 4. To make it safer, __________ is needed before a transfusion. A. an operation B. a reaction C. a healthy man D. cross matching of the blood 5. This passage wants to tell us __________. A. who Oswald Robertson was B. the first transfusion C. how blood banks work D. what blood banks are like