前牙区上牙盖过下牙，超过切1／2以上者为（）
A.覆
B.覆盖
C.Ⅰ°深覆
D.Ⅱ°深覆验
E.Ⅲ°深覆
参考答案：C
The duties of a policeman are _____ than ____ .
A．dangerouser ; a teacher
B．more dangerous ; a teacher
C．greater danger ; those of a teacher
D．more dangerous ; those of a teacher
输入输出接口的英文缩写是( )。
A．I/O
B．ROM
C．RAM
D．CD-ROM
