关节活动度减少的原因可能是（）
A.关节周围肌肉瘫痪
B.关节囊挛缩
C.韧带断裂
D.韧带松弛
E.周围神经损伤
参考答案：B
He is _ Ben some questions ____ public signs. [ ]
A. asks; to
B. asks; as
C. asking; about
D. asking; to
请简述尿常规酸碱度（pH）的参考值
