标题拒绝进入表格下方

Question

正如您所看到的，即使将标题放在表格环境的末尾也不起作用。

\documentclass[twocolumn]{article}
\usepackage{tgbonum}
\usepackage[T1]{fontenc}
\usepackage{geometry}
\usepackage{chemstyle}
\usepackage{chemfig}
\usepackage{booktabs}
\usepackage{siunitx}
\DeclareSIUnit{\Molar}{\textsc{m}}
\usepackage[super]{natbib}
\usepackage{hyperref}
\usepackage{graphicx,float}
\usepackage{chemnum}
\usepackage{chemscheme}
\usepackage[font=small,labelfont=bf]{caption}
\usepackage{color}

 \geometry{
 a4paper,
 total={170mm,257mm},
 left=20mm,
 top=20mm,}

\begin{document}
\title{XYZ}
\author{\small{One and Two}}
\date{\small{30\textsuperscript{th} May, 2018}}


\twocolumn[
  \begin{@twocolumnfalse}
    \maketitle
    \begin{abstract}
      ...
    \end{abstract}
  \end{@twocolumnfalse}
]

\section{Introduction}

\begin{table}[!htbp]
\centering 
\setlength{\tabcolsep}{4pt}
\begin{tabular}{lccl}
\toprule
P& S\\
\midrule
\textbf{1}x&GQVGRQLAIIGDDINR\\
\textbf{2}y&123\\
\textbf{3} z&123\\
\textbf{4} a&123\\
\textbf{5} b&123 \\
\bottomrule
\end{tabular}
\caption{Thicker horizontal lines above and below the table.}
\label{t:p}
\end{table}

\bibliographystyle{rsc}
\bibliography{REF.bib}


\end{document}