[Tex/LaTex] How to hide the other items completely when I use “pause” operation in beamer

Question

When I compiling the following codes：

\begin{frame}
  \begin{itemize}
    \item a
    \pause
    \item b
    \pause
    \item c
  \end{itemize}
\end{frame}

It's effect is the following:

As we can see that when "a" appears we can also see "b" and "c". I want to know how to hide "b" and "c" completely?

Answer 1

This should have been comment but there this can't be put.

This hides them

\documentclass{beamer}
%\setbeamercovered{transparent}
\begin{document}
\begin{frame}
  \begin{itemize}
    \item a
    \pause
    \item b
    \pause
    \item c
  \end{itemize}
\end{frame}

It won't if you uncomment the line

%\setbeamercovered{transparent}