题目内容：

Karl Landsteiner first thought of naming blood types in 1900. He put blood into four types. These four blood types were named A, B, AB, and O. Blood type O is the most common around the world. Blood type A is the second most common. and type AB is the least common.

Doctors try to give blood to a person according to the person’s blood type. Blood type O can be given to a person with any other blood type, but doctors also need to make sure that the “RH factor (因子)” in patients’ blood matches the blood they are given. If people have one kind of protein (蛋白质) in their blood, they are RH positive (Rh+). If people do not have the protein, they are Rh negative (Rh-). Most people are Rh+.

If a mother has an Rh- blood type, she may have trouble when she has a baby. If her baby is Rh+, the baby’s blood may mix with the mother’s blood before the baby is born. The mother’s blood will change. If the mother has another Rh+ baby, the mother’s blood will attack the baby’s blood. The baby may die or become sick. Doctors have to watch the mother and baby carefully in these cases.

1.Who named the blood type?

A. Albert Einstein.B. Thomas Edison.      

C. Albert Schweitzer.D. Karl Landsteiner.

2.Which blood type is the second most common in the world?

A. Blood type A.B. Blood type B.   

C. Blood type AB.D. Blood type O .

3.What must be in a person’s blood if the person is Rh+?

A. Special water.B. A special protein. C. Baby’s blood.D. Electricity.

4.Which of the following might be dangerous for the baby?

A. Mother (Rh+) / baby (Rh+).  B. Mother (Rh+) / baby (Rh-).

C. Mother (Rh-) / baby (Rh+).    D. Mother (Rh+) / baby (Rh-).

5.Where is this article most probably taken from?

A. A story book.       B. A news report.      C. A science magazine. D. An ad