短文改错。

     Last summer I learnt to ride a bicycle. At first,I was unable to control it's direction. Sometimes

I fall to the right or to the left. But I asked my father to tell me how I could ride straightly. He didn't

answer me directly. Instead, he took me to side of the street. "Can you find some bike track that is

really straight?" asked my father. I watched more carefully and shook my head ."No" he said, "in fact

neither of the tracks is always straight. But just by correct the direction every now and then, you had

already gone forward."

类风湿关节炎的基本病理特征是（）。

A.韧带炎

B.软骨炎

C.肌腱炎

D.附着点炎

E.滑膜炎