```tex
\documentclass[a4paper,UTF8,twoside]{article}
\usepackage{amsmath}
\usepackage{amssymb}
%\use...
```tex
\documentclass[a4paper,UTF8,twoside]{article}
\usepackage{amsmath}
\usepackage{amssymb}
%\usepackage{mathtools}
\usepackage[margin=20mm]{geometry}
\usepackage{cases}
\begin{document}
\begin{numcases}{}
\text{in } L^p, &$1
一周热门 更多>