发生膝骨性关节炎的危险因素不包括（）
A.年龄在55岁以上
B.肥胖
C.家庭病史
D.文娱活动中突然转向
E.高度接触性运动
参考答案：D
Read and order. 读一读，给下面的句子排序。
( ) I can't see her, but she's quiet.
( ) What is the girl doing now?
( ) She isn't singing.
( ) Yes.
( ) I don't know.
简述各种标识、标牌的布局摆放的工作程序。
