用于孤立前磨牙和磨牙（）
A.圈形卡环
B.回力卡环
C.对半卡环
D.延伸卡环
E.联合卡环
参考答案：C
--- Tom wants to know_____________.
--- I don't know, either. He said he would phone me as soon as he came back.
A．when Dad comes back
B．when did Dad come back
C．when Dad will come back
D．when does Dad come back
