在方丝弓矫治器的应用过程中，为关闭拔牙间隙常采用在弓丝上弯制
A．水平曲
B．欧米加曲
C．泪滴型曲
D．垂直张力曲
E．小圈曲
参考答案：C
In 1863, President Lincoln issued a declaration calling for the last Thursday of November_______ as
a day of thanksgiving.[ ]
A. being observed
B. observed
C. observing
D. to be observed
绝缘隔板只允许在35kV及以下电压的电气设备上使用
