刚构桥顺桥方向外侧间的长度称为（）。

A、桥梁长度

B、桥孔总长

C、梁的全长

D、桥梁全长

创建一个名为student的新类，保存新类的类库名称是mylib，新类的父类是Person，正确的命令是______。

A．CREATE CLASS mylib OF student As Person

B．CREATE CLASS student OF Person As mylib

C．CREATE CLASS student OF mylib As Person

D．CREATE CLASS Person OF mylib As student