Johnson,     to grasp the chance to become a doctor,decided to take up teaching.[ ]

A. fail  

B. failed        

C. to fail  

D. having failed

我国在陆地上的国家统一的平面坐标系统是采用( )。

A．高斯—克吕格平面直角坐标系
B．UTM坐标系
C．笛卡儿坐标系
D．GIS坐标系