When you cut your skin，you bleed．If a person loses a lot of blood，he will become ill and may die．Blood is very important．People have always known that．At one time，some people even drank blood to make them strong!

When doctors understand how blood goes around inside the body，they try ways of giving blood to people who need it．They take blood from the healthy people and give it to people who need it．This is called"blood transfusion"（输血）．The blood goes from the arm of the healthy person into the arm of the sick person．

But there are two problems．First，it does not always work．Sometimes people die when they are having blood transfusion．Later，doctors find that we do not all have the same kind of blood．There are four main groups of blood﹣﹣﹣O，A，B and AB．Almost all of us have blood of one of these groups．They also find that they can give any of the four groups of blood to people to people of group AB．But they find that they must give A﹣group blood to A﹣group people and B﹣group blood to B﹣group people．I have O﹣group blood and the doctor told me that I could give blood to anyone else safely．

There is another problem．To give blood of the right kind，doctors have to find a person of the right blood group．Often they can not find a person in time．If they have a way to keep the blood until someone needs it，they can always have the right kind of blood．At first，they find if they make it very cold，they can keep the blood in bottles for fifteen to twenty days．Then they find out how to keep it longer．In the end they find a way of keeping blood for a very long time．

We call a place where we keep money a"bank"．We call a place where we keep blood a"blood bank"．One day，when you grow up，you may decide to give blood to a"blood bank"．In this way，you may stop someone from dying．Or perhaps one day you may become ill．You may need blood．The"blood bank"will give it to you．

58．Why do people sometimes die when they have blood transfusion？ 　　

A．	Because they are not given the right kind of blood．
B．	Because they are given the same kind of blood．
C．	Because the doctors have lost lots of blood．
D．	Because the doctors are unhealthy people．

59．Which of the following is TRUE？ 　　

A．	Blood transfusion is drinking blood．
B．	There are only three groups of blood．
C．	The writer can give blood to A﹣group people．
D．	The writer can't give blood to any other person safely．.

60．We set up the blood bank to 　　．

A．	keep more money for sick people
B．	make more money for people who need it
C．	keep different groups of blood as much as possible
D．	give the right kind of blood to the people who need in time

61．Which of the following is NOT mentioned in the passage？ 　　

A．	What"blood transfusion"is．
B．	Blood is very important to us
C．	There are four main groups of blood．
D．	Where the blood bank should be built．