依照国际牙科联合会的记录法【（×）DI法】，右下第一恒磨牙应记录为（）。
A.6
B.46
C.46
D.30
参考答案：C
_______ he worked hard, _______ he failed in the exam. [ ]
A. Although, but
B. Though, but
C. Although, /
D. But, although
原位溶血是指红细胞的破坏发生于
A．血管
B．骨髓
C．脾
D．肝
