– Li Ping speaks English very well.

– _______. Going to the English club helps him a lot.

A. So does he                 B. So do I                  C. So he does

双代号网络图绘制时，宜避免箭线交叉，当交叉不可避免时，可采用( )。

A．过桥法

B．断线法

C．指向法

D．母线法

E．波形线法