题目

One cold winter morning, an old woman had to go to see her doctor. When she walked into the doctor's office, she told him that her right leg hurt and sometimes she could not walk. She asked him what was wrong. She told him that she had never had such a feeling before.The doctor checked the old woman carefully, then he said, You're in good health for a woman of your age. I think the trouble in your right leg is just a matter of old age . We get all kinds of illness as we get older. The trouble will almost certainly end in spring.I don't think so, doctor! she said. My left leg is well, and it's根冠属于____________组织