Although acupuncture has been practiced in China for 2,000 years, its use in the Western world is still very new. Several hospitals in the United States are【31】experimenting with acupuncture as a way of treating pain. An American journalist【32】stood beside a patient during an operation in Shanghai recently【33】the process and its effects. To keep the patient from【34】pain during the operation, four needles were used, each about an inch and a half【35】Two needles were inserted under the skin on each side of the【36】neck. The tops of the needles【37】attached to wires which led【38】a small electrical device. Throughout the【39】the patient talked calmly to those standing aroun him,【40】that the felt perfectly normal. At one point he stretched out his hands and moved his【41】toes to show that only his chest and neck were affected. How does acupuncture work? How is it able to【42】a patient from feeling pain? No very satisfactory answer has been given, but there are【43】least three theories.【44】doctors believe that acupuncture somehow produces an effect【45】the central nervous system. Others believe that acupuncture【46】a chemical change in the body's fluids. Still another theory is that the needles make contact【47】an unknown system of energy in the body【48】travels along certain routes under the skin. The true explanation may be one of【49】or a combination of more than one. It may be【50】entirely different. (1)