A virtual stochastic process is constructed so that the basic random variable becomes the value of the stochastic process at certain instants of time.

基于概率密度演化的基本思想，构造一个虚拟随机过程，使得随机结构动力反应的极值为该虚拟随机过程的截口随机变量。

youdao

The basic definition-- the expected value of some random variable x--E--I guess I should have said that a random variable is a quantity that takes on value.

最基本的定义,某一个随机变量X的期望值E,我应该提到过,随机变量是一个可以取值的数

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