Which are the essentials of Daozhuai Niujiuwei?

A、Clench the fists with strength.;
B、When bending the hips and knees in the horse-riding stance, the angle between the leg and the ground should be smaller than 45 degrees.;
C、The angle between the foreleg and the ground in bow-step stance should be smaller than 45 degrees.;
D、The knee joint of the hind leg should be straight