And each of them are independent, standard, normal, normally distributed random variables.
而且每一个都是独立的、标准的、正态的、正态分布的随机变量。
英语百科
Standard normal deviate
（重定向自Standard normal variable）
A standard normal deviate (or standard normal variable) is a normally distributed random variable with expected value0 and variance1. A fuller term is standard normal random variable. Where collections of such random variables are used, there is often an associated (possibly unstated) assumption that members of such collections are statistically independent.