全口义齿上颌中切牙的切缘位于上唇下（）
A.0.5～1mm
B.1～2mm
C.2～3mm
D.0.5mm以下
E.3mm以上
参考答案：B
Everything works out well. ____, we are sure that the experiment will be completed on time. [ ]
A. Therefore
B. While
C. However
D. Otherwise
Lb4B2076冲洗液从钻杆进入孔底，从钻具与孔壁之间返回的冲洗方式称为反循环冲洗。
