How to create invisible item in Beamer Overlays case by case?

Please allow me to explain my situation. I am using Beamer overlay for a quiz. (And I love the pdf output). So, I give the students multiple choices on first slide. And next slide they get the answer. But, I want to add an additional comment after the answer, to describe little more about the topic. Here is what I have.

\begin{frame}{Programming Basics}
\begin{enumerate}
\item<1> !
\item<1> @
\item<1> ::
\item<1-2> ;
\item<2> Only show this in second slide, ; I am comment
\end{enumerate}
\end{frame}


I like \setbeamercovered{transparent} so I don’t want to set to invisible. I just want the last item to show up after the answer, without a grey transparent item showing up on first slide, because this can give them a hint!!! (See the attached image)

I did some research but could not find the answer. Thank you.

\invisible is your new friend

\documentclass{beamer}
\setbeamercovered{transparent}
\begin{document}
\begin{frame}{Programming Basics}
\begin{enumerate}
\item<1> !
\item<1> @
\item<1> ::
\item<1-2> ;
\invisible<1>{\item Only show this in second slide, ; I am comment}
\end{enumerate}
\end{frame}
\end{document}


• This is almost exactly what I want. Thank you. Is there a way to remove a numbering in it. (item 5th) Apr 25 '16 at 16:23
• Put it outside the itemize-environment or inside the 4th item (maybe with a new line)? Apr 25 '16 at 16:25
• A newline works but, what if my answer is item 1 or 2, it messes up the formatting. Apr 25 '16 at 16:31
• @Cricrazy Where do you want your comment to be if 1 is the answer? After item 1 or at the end? Apr 25 '16 at 16:36
• Sam, I got it working. I wanted it to be outside the itemize at the end. here is what I did. \vspace{10mm} \textbf{\invisible<1>{Semi-colon is used for commenting}}} Thanks a lot. Apr 25 '16 at 16:41