全口义齿在排前牙时要求牙尖或切缘高出牙合平面的是（）
A.A
B.B
C.C
D.D
E.E
参考答案：D, E
Until the start of the Industrial Revolution, mankind was poor, hungry, and constantly at the _______ of disease and natural disasters．
A．power
B．limit
C．control
D．mercy
80×5的积是[ ]
A．两位数
B．三位数
C．四位数
