您好！作者姓名、电子邮件等未显示。感谢您的帮助

Question

\documentclass[a4paper,titlepage,oneside, reqno]{amsart}
\usepackage[left=2.7cm, right=2.5cm, top=3cm]{geometry}
\usepackage[utf8]{inputenc}
\usepackage[T2A, T1]{fontenc}
\usepackage[numbers]{natbib}
\usepackage[dutch,polish,swedish,french,german,russian,main=english]{babel}
\let\plll\lll
\let\lll\relax
\usepackage{lmodern}
\usepackage[tipa,combine]{ucs}
\usepackage[colorlinks]{hyperref}
\hypersetup{colorlinks,linkcolor={green!55!black},citecolor={green!55!black},urlcolor={green!55!black}} \usepackage{url}
\usepackage[pdftex]{graphicx}
\usepackage{amsthm,amssymb,bm}
\usepackage{thmtools}
\usepackage{environ}
\usepackage{nicefrac}  
\usepackage[dvipsnames]{xcolor}
\usepackage{tikz}
\usepackage[affil-it]{authblk}
\usepackage{epstopdf}
\usepackage{amsfonts,amssymb,amsbsy}
\usepackage{mathtools}
\usepackage{amsmath}
\usepackage{nccmath}
\usepackage{tabu}
\usepackage{tabularx}
\usepackage{multirow}
\usepackage{bbm}
\usepackage{comment}
\usepackage{microtype} 
\usepackage{placeins}
\makeatletter
\let\mytagform@=\tagform@
\def\tagform@#1{\maketag@@@{\color{green!55!black}(#1)}}
\makeatother
\newcommand{\eqnumcolor}{\color{green!55!black}}
\newtheorem{theorem}{Theorem}[section]
\newtheorem{lemma}[theorem]{Lemma}
\newtheorem{proposition}[theorem]{Proposition}
\newtheorem{corollary}[theorem]{Corollary}
\newtheorem{observation}[theorem]{Observation}
\newtheorem{definition}[theorem]{Definition}
\newtheorem{remark}[theorem]{Remark}
\newtheorem{example}[theorem]{Example}
\newtheorem{assumption}[theorem]{Assumption}
\newtheorem{problem}[theorem]{Problem}
\parindent0mm
\usepackage{helvet}
\usepackage{titlesec}
\usepackage{parskip}

\titleformat{\chapter}
  {\normalfont\fontsize{12}{15}\sffamily\bfseries}
  {\thechapter}
  {0.5em}
  {}

\titleformat{\section}
  {\normalfont\fontsize{10}{15}\sffamily\bfseries}
  {\thesection}
  {0.5em}
  {}

\titleformat{\subsection}
  {\normalfont\fontsize{8}{13}\sffamily\bfseries\slshape}
  {\thesubsection}
  {0.5em}
  {}
  
\title[xyz]{xyz}

\author{}
\email{}


\begin{document}
\maketitle

您好！作者姓名、电子邮件等未显示。感谢您的帮助。