Expex interlinear centering includes punctuation

Question

As you can see in the image below, when using glwordalign=center, the punctuation in \gla counts as part of the word. As a result, \glb and \glc are centered not just on the word but also on the punctuation. How can I prevent the punctuation from being counted as part of the word so that only the words align but the punctuation is still there in its proper place?

Here is the MWE:

\documentclass{book}        
\usepackage{expex}    
\lingset{glwordalign=center}

\begin{document}    
\exdisplay
\begingl
  \gla "aaaaa aaaaaaa!" aaaa aaaa aaaa... //      
  \glb bbbbb bbbbbbb bbbb bbbb bbbb //      
  \glc ccccc ccccccc cccc cccc cccc //      
\endgl
\xe    
\end{document}

P.S. ignore the wrong starting quotation mark.

Answer 1

You can use the \nogloss macro to mark unglossed elements in the \gla line, plus the @ to remove the space. Note that the spaces around the @ are required.

\documentclass{book}        
\usepackage{expex}    
\lingset{glwordalign=center}

\begin{document}    
\exdisplay
\begingl
  \gla \nogloss{``} @ aaaaa aaaaaaa @ \nogloss{!''} aaaa aaaa aaaa @ \nogloss{\ldots} //      
  \glb bbbbb bbbbbbb bbbb bbbb bbbb //      
  \glc ccccc ccccccc cccc cccc cccc //      
\endgl
\xe    
\end{document}