His failure in the exam suggested that he __________ the teacher’s instructions.

A．can’t have followed

B．needn’t have followed

C．mustn’t have followed

D．shouldn’t have followed

三角高程测量是根据两点的水平距离和竖角计算两点的（）。

A.高差

B.竖角

C.坐标

D.倾斜距离