单选题
In medicine, blood type is the classification of red blood cells by the presence of specific substances on their surface. In the early part of the 20th century, physicians discovered that blood transfusions often failed because the blood type of the recipient was not compatible with that of the donor. In 1901 the Austrian doctor Karl Landsteiner classified blood types and discovered that the hereditary blood factor is of great importance in blood transfusions because it creates reactions that can threaten the life of newborn infants. The four blood types are known as A, B, AB, and O. Blood type A contains red blood cells that have a substance A on their surface. This type of blood also contains an antibody directed against substance B, which can be found on the red cells of persons with blood type B. Type B blood contains the opposite things. Blood type AB contains neither antibody, but red cells in this type of blood contain both A and B substances. In type O blood, neither substance is present on the red cells, but the individual is capable of forming antibodies directed against red cells containing substance A or B, If blood type A is transfused into a person with B type blood, anti-A antibodies in the recipient will destroy the transfused A red cells. Because O type blood has neither substance on its red cells, it can be given successfully to almost any person. Persons with blood type AB have no antibodies and can receive any of the four types of blood; thus blood types O and AB are called universal donors and universal recipients, respectively. Other hereditary(遗传的) blood-group systems have subsequently been discovered, for example, the Rh blood factor. And nowadays more than twenty additional blood types have been discovered. Their importance is obvious.
单选题
In the early part of the 20th century, physicians discovered that blood transfusions often failed because ______.
【正确答案】
B
【答案解析】根据文章第一段第二句话来做，注意be compatible with “与……兼容”；be suitable for“适合……”。
单选题
Which of the following is NOT true according to the passage?
【正确答案】
D
【答案解析】在D项中，错误在于多了“neither”一词，使整句话意思完全相反。
单选题
If a patient whose blood type is O needs blood transfusion, who can be the donor?
【正确答案】
D
【答案解析】文章讲到O型血的人是universal donors，但不是universal recipients。因为在第二段最后一句“Persons With blood type AB have no antibodies and can receive any of the four types of blood; thus blood types O and AB are called universal donors and universal recipents, respectively.”中respectively是“各自地，独立地”的意思。同时另一句“In type O blood, neither substance is present on the red cells, but the individual is capable of forming antibodies directed against red cells containing substance A or B.”其句意是：O型血的人红细胞中没有该物质，但个体的人能形成抗A或B型红细胞的抗体。所以，只有O型血的人能给O型人输血。
单选题
A baby's blood type is decided by ______.
【正确答案】
B
【答案解析】此题可根据常识来做，孩子的血型由父母决定。
单选题
The best title for this passage would be ______.