计算了电子-正电子散射的16 种极化散射截面.根据角分布的特征，它们可以分为三大类，其前向奇性分别是 sin-4( θ /2) 、sin-2( θ /2) 和1.也计算了电子-电子散射的16 种极化散射截面，它们既可以按前向奇性分为三大类，也可以按后向 奇性分为三大类.三类奇性的特征与电子-正电子散射类似.对于三类奇性的出现给出了直观的物理说明.

The 16 polarized cross sections for electron-positron scattering are calculated. They can be grouped into three classes according to the behavior of the angular distribution. The three classes have singularities sin-4( θ /2) ，sin-2 ( θ /2 ) and 1 in the forward direction， respectively. The 16 polarized cross sections for electron-electron scattering are also calculated. They can be grouped into three classes according to their singular behavior in either the forward direction or the backward direction. The singularities are similar to those for electron-positron scattering. A simple physical explanation is presented for the singular behavior.