Market demand is a stochastic variable which brings difficulty for most profit by ordering right goods.

市场需求量是一个随机变量,它给订货者追求最大利润,确定最优订货量带来了困难.

Usually you want every instantiation of a distribution to represent an uncorrelated stochastic variable, which means that you should a new engine for each one.

通常你要分配的每个实例化代表着不相关的随机变量，这就意味着你应该为每一个新的引擎。