—Charlie has been nowhere       for three days. What has happened to him?

—Didn’t you know he had gone to Hong Kong?

A．in sight

B．in place

C．in face

D．in use

水调自动化中，对同一个水电厂同一时刻的入库流量进行计算，一小时后手工计算结果和之前自动计算的的结果不一致，可能的原因是（）。

A.算法文件不一致

B.可能计算发生溢出

C.数据源发生了改变

D.数据库故障