菠菜鸡蛋汤

$$ \newcommand{\indep}{\mathrel{\perp\mkern-10mu\perp}} \newcommand{\P}{\mathbb{P}} \newcommand{\R}{\mathbb{R}} \newcommand{\E}{\mathbb{E}} \newcommand{\Var}{\operatorname{Var}} \newcommand{\Cov}{\operatorname{Cov}} \newcommand{\1}[1]{\mathbf{1}\\{#1\\}} $$