Nothing can stop a _____ student _____ his mind to give up his studies.   

A．promised; to change

B．promised; changing

C．promising; changing

D．promising; to change

测量上通常把实测高差与理论值的差值称为（）。

A、路线误差

B、系统误差

C、高差闭合差

D、偶然误差