间接固位体
参考答案：
辅助直接固位体固位的装置，是为防止义齿翘起、摆动、旋转、下沉而设计的固位装置。主要是为了加强义齿的稳定性。
Is there anyone in your class who__________the car accident that happened in front of our school this
morning? [ ]
A. witnessed
B. observed
C. introduced
D. predicted
排水立管
