单项选择题
A.精车复合循环B.纵向粗车复合循环C.端面粗车复合循环D.仿形粗车复合循环
A.G70P1Q2;B.G70P=N1Q=N2;C.G70P1.Q2.;D.G70PNI QN2;
A.G70B.G71C.G72D.G73