Wouldn't it be nice if students had to go to ________ school only four days ________ week?

A．不填； a

B．不填； the

C．the; a

D．the; the

膝骨关节炎表现为( )

A．是骨关节炎最为常见的表现
B．关节疼痛活动后加重，休息后缓解
C．膝外翻畸形
D．膝内翻畸形
E．以上均是