这个D项里面的without well-known distribution是什么意思啊

问题如下：

A copula function C transforms an n-dimensional function on the interval [0, 1] into a unit-dimensional one：

Which of the following statements is not correct ?

选项：

A.

ρ_F is the correlation matrix structure of the joint cumulative function between $G_i{(u_i)}$ and Fn.

B.

$F_1^{-1}$ is used in the mapping process.

C.

Fn is the joint cumulative distribution function.

D.$G_i{(u_i)}$ are marginal distribution without well-known distribution properties.

解释：

A is correct.

考点：copula function

解析：G已经被mapping 到F了，ρ_F是mapping之后Fn的相关性矩阵。