A、Expensive drugs may not prove the most effective. B、The workings of the mind may help patients recover. C、Doctors often exagge

Western doctors are beginning to understand what traditional healers have always known—the body and the mind are inseparable.
    Until recently, modern urban physicians heal the body, psychiatrists the mind, and priests the soul. However, the medical world is now paying more attention to holistic medicine, which is an approach based on the belief that people’s state of mind can make them sick or speed their recovery from sickness. Several studies show that the effectiveness of a certain drug often depends on the patient’s expectations of it.
    For example, in one recent study, psychiatrists at a major hospital tried to see how patients could be made calm. They divided them into two groups. One group was given a drug while the other group received a harmless substance instead of medicine without their knowledge.
    Surprisingly, more patients in the second group showed the desired effect than those in the first group. In study after study, there’s a positive reaction in almost one-third of the patients taking harmless substances. How was this possible? How can such a substance have an effect on the body? Evidence from a 1997 study at the University of California shows that several patients who received such substances were able to produce their own natural drug, that is, as they took the substance their brains released natural chemicals that act like a drug. Scientists theorized that the amount of these chemicals released by a person’s brain quite possibly indicates how much faith the person has in his or her doctor.
    Questions 13 to 15 are based on the passage you have just heard.
    13. According to the speaker, what are western doctors beginning to understand?
    14. What does the recent study at a major hospital seem to prove?
    15. What evidence does the 1997 study at the University of California produce?