无牙颌患者下颌处于正中关系位时上下颌牙槽嵴顶间的距离称为（）
A.开口度
B.息止合间隙
C.垂直距离
D.颌间距离
E.覆合
参考答案：D
—Why do you suggest we buy a new machine?
—Because the old one has been damaged ______.
A．beyond reach
B．beyond repair
C．beyond imagination
D．beyond description
农药污染土壤的的途径有哪些？
