若BD光盘容量为40GB，光驱读取全部数据要170s，则该光驱的数据传输率大约是（）Gbps。
A、2
B、0.2
C、3
D、2.5
参考答案：A
It was at that school _________ he realized his dream _________ he was going to be a teacher.
A．that; that
B．that; which
C．where; that
D．where; which
恒牙骀建骀的关键时期是
A．新生儿期B．婴儿期C．幼儿期D．混合牙列阶段E．年轻恒牙列阶段
