题目内容：

When you go to the doctor, you like to come away with a prescription．It makes you feel better to know you will get some medicine. But the doctor knows that medicine is not always needed. Sometimes all a sick person needs is some reassurance that all will be well. In such cases the doctor may prescribe a placebo.

A placebo is a sugar pill, a harmless shot, or ail empty capsule. Even though they have no medicine in them, these things seem to make people well. The patient thinks it is medicine and begins to get better. How does this happen?

The study of the placebo opens up new knowledge about the way the human body can heal itself. It is as if there was a doctor in each of us. The doctor will heal the body for us if we let it. But it is not yet known just how the placebo works to heal the body. Some people say it works because the human mind fools itself. These people say that if the mind is fooled into thinking it got medicine, then it will act as if it did, and the body will feel better.

Placebos do not always work. The success of this treatment seems to rest a lot with the relationship between the patient and the doctor. If the patient has a lot of trust in the doctor and if the doctor really wants to help the patient, then the placebo is more likely to work. So in a way, the doctor is the most powerful placebo of all.

A placebo can also have bad effects. If patients expect a bad reaction to medicine, then they will also show a bad reaction to the placebo. This would seem to show that a lot of how you react to medicine is in your mind rather than in your body. Some doctors still think that if the placebo can have bad effects it should never be used. They think there is still not enough known about it.

The strange power of the placebo does seem to suggest that the human mind is stronger than we think it is. There are people who say you can heal your body by using your mind. And the interesting thing is that even people who swear this is not possible have been healed by a placebo．

1.What do we know about placebo according to the passage?

A. It contains some sort of medicine.

B. It won’t function if you are negative about medicine.

C. People who don’t believe placebo can’t be healed by it.

D. Patients and doctors know clearly how it helps to heal the body.

2.Why is the doctor sometimes the most powerful placebo?

A. The patient needs help badly．

B. The patient believes in the doctor．

C. The doctor knows better about your body．

D. The doctor has carefully studied medicine．

3.What does the underlined word “it” in Paragraph 5 refer to?

A. The placebo.    B. The bad effect.

C. The body.    D. The medicine.

4.What is the passage mainly about?

A. Placebo：Work on Your Mind

B. Placebo：The Most Powerful Medicine

C. Placebo：The Best Doctor

D. Placebo：Heal Your Body