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\begin{document}
\section{tables}
\begin {table}[ht!]
%\caption {Text} \label{tab:title}
\begin{center}
\begin{tabular}{ | l | l | l | l | p{3cm} |}
\hline
region & nodes &depl.width & expression &comment \\ \hline
x & B1C4 &Wn & $Wn=Wn(VjCex)$ &width of depletion is function of voltage bias \\ \hline
xx & BC3 &XWn & $XWn=XWn(XVjCex)$&width of depletion is function of voltage bias \\ \hline
\end{tabular}
%\caption {Should be a caption}
\caption {XCJC:Fraction of the C-B depletion capacitance under
the E.$Vtc=(Vcv,Vb2c1)$,$Vtex=(Vtexv,Vb1c4)$} \label{tab:t05}
\end{center}
\end {table}
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\end{document}