Software design is a (46) process. It requires a certain amount of fl air on the part of the (47) . Design can not be learned from a book . It must be practiced and learnt by experience and study of existing systems. A well (48) software system is straightforward to implement and maintain , easily (49) and reliable. Badly (48) software systems, although they may work are (50) to be expensive to maintain , difficult to test and unreliable.

A．design

B．designing

C．designed

D．designs

建设永久测量标志，应当遵守的基本规定有（）

A.使用国家规定的测绘基础的测绘标准

B.选择有利于测量标志长期保护和管理的点位

C.地图标志占用土地的范围不超过500平方米

D.应当对永久性测量标志设立明确标记

E.委托当地有关单位指派专人负责保管