根据短文理解, 从A、B、C、D四个选项中选择最佳答案填空。

    One cold morning, an old woman had to 1 her doctor. When he came, she 2 him that her right leg hurt, and that sometimes she could  3 walk. She asked him what was  4  , as she had  5got such feeling.

    The doctor looked her over carefully, and then he said, "You are in a good 6  for a woman of your age. I think the trouble in your right leg is just a matter of old age catching up with you. We get all kinds of illness  7  we get older. The trouble will almost certainly 8  in spring." "I don't think so, doctor," she said. "My left leg is  9 , and it is 10  age as my right leg."