所以如果我试着用这三边构成一个平行六面体，如果点P不在这个平面内，这个平行六面体就会有体积。

So, if I try to form a parallelepiped with these three sides, and P is not in the plane, then it will have some volume.

youdao

在特征集的基础上，讨论了其参数导数的构成情况，用有限个点和函数表示了无穷个参数导数的情形。

Based on characteristic set, the case of infinity parameters is described by using of finite value and functions.

youdao