阅读理解。
Carbon monoxide(一氧化碳) poisoning kills and injures many people and animals around
the world. The gas has been a problem since people first began burning fuels to cook food or to
create heat. It is a problem in all parts of the world that experience cold weather.
Carbon monoxide is called the silent killer because people do not know it is in the air. The gas
has no color. It has no taste. It has no smell. It does not cause burning eyes. And it does not cause
people to cough. But it is very deadly. It robs the body of its ability to use oxygen.
Carbon monoxide decreases the ability of the blood to carry oxygen to body tissues. It does this
by linking with the blood. When the gas links with the blood, the blood is no longer able to carry
oxygen to the tissues that need it.
Damage to the body can begin very quickly from large amounts of carbon monoxide. How
quickly this happens depends on the length of time a person is breathing the gas and the amount of
the gas he or she breathes in.
Carbon monoxide poisoning has warning signs. But people have to be awake to recognize them.
Small amounts of the gas will cause a person's head to hurt. He or she may begin to feel tired. The
person may feel sick. The room may appear to be turning around. The person may have trouble
thinking clearly. People develop severe head pain as the amount of gas continues to enter their blood.
They will begin to feel very tired and sleepy. They may have terrible stomach pains.
Medical experts say carbon monoxide affects people differently. For example, a small child will
experience health problems or die much quicker than an adult will. The general health of the person
or his or her age can also be important. An older adult with health problems may suffer the effects of
carbon monoxide more quickly than a younger person with no health problems. People with heart
disease may suffer chest pains. They may begin to have trouble breathing.
1. Why is carbon monoxide called the silent killer?
A. Because it tastes and smells good.
B. Because it is not easily noticed.
C. Because it kills and injures people.
D. Because it always harm people..
2. How does carbon monoxide harm people?
A. It makes people's blood unable to move.
B. It decreases the amount of blood in the body.
C. It makes body tissues full of blood.
D. It makes the blood less able to carry oxygen.
3. When people breathe in small amounts of the gas, they may ________.
A. feel a little dizzy
B. suffer a severe headache
C. go around in the room
D. have a terrible stomachache
4. Which of the following about carbon monoxide poisoning is true?
A. Adults are affected more seriously than children.
B. Young people are more severely affected than old people.
C. People in poor health may have more severe consequences.
D. People with heart problem only suffer from chest pains.
5. The purpose of the passage is to ________.
A. warn people not to burn fuels to keep warm in the winter
B. list the damages that carbon monoxide brings to people
C. give advice on how to avoid carbon monoxide poisoning
D. introduce some knowledge about carbon monoxide poisoning