固定矫治器治疗中的牙釉质脱矿发病率达（）
A.10％
B.20％
C.30％
D.50％
E.90％
参考答案：D
If it had been fine yesterday, we could have watched that air show. But it _____________ all day.
A．has rained
B．had rained
C．rained
D．rains
唐高宗至唐德宗铜镜类型及艺术风格（650~804）。
