塑化与根管充填治疗（）
A.都可治疗根尖周炎
B.都要彻底拔髓
C.都要严格扩挫根管
D.均可通过X线显影了解治疗结果
E.以上都对
参考答案：A
________ something wrong with the machine, I am afraid.
A．There seems to have
B．There seems to be
C．He seems to be
D．It seems to be
判断梁横截面上的切应力作用线必须沿截面边界切线方向的依据是：（）
A.横截面保持平面
B.不发生扭转
C.切应力公式应用条件
D.切应力互等定理
