发现牙根进入上颌窦首先应做的是（）
A.拍X线片
B.从穿孔处掏根
C.冲洗上颌窦
D.开窗取根
E.服抗菌药物
参考答案：A
--- This dress is a little . Can you show me another one?
--- What about the orange one?
A．cheap
B．high
C．low
D．Expensive
顶级域的划分模式为组织模式和______。
