Only when I left home to go to college ___ how much my mother had done for me.

A．did I realize

B．I realized

C．had I realized

D．I had realized

在加工整圆时，可以通过（）插补方式进行编程加工。

A．角度加半径

B．极坐标圆弧插补

C．插补参数I，J，K

D．前面几种均可