On this example, the word usando is not being hyphenated, but the word Comandos is. If I force a hyphen on the first word usan-do, it is hyphenated correctly:
\documentclass[10pt,openright,twoside,a5paper]{memoir}
\usepackage[brazil]{babel}
\usepackage[showframe]{geometry}
\setlength{\parindent}{1.6cm}
\begin{document}
\frenchspacing
\selectlanguage{brazil}
No entanto, você pode compilar os documentos \LaTeX usando os seguintes
comandos, que devem ser digitados no \emph{Prompt de Comandos} do Windows ou no
\emph{Terminal} do Mac ou do Linux:
\end{document}
test2.tex:11: Overfull \hbox (4.94724pt too wide) in paragraph at lines 11--14[]\OT1/cmr/m/n/10 No en-tanto, voc pode com-pi-lar os do-cu-men-tos L[]T[]Xusando
Is there some way to debug the LaTeX hyphenation? For example, I can debug the overfull boxes, using \usepackage[showframe]{geometry} or \usepackage{showframe} in my preamble. So, is there some package I can include which helps me to find out why LaTeX is not hyphenating some words?
Related questions:


\LaTeXand what follows, so tex considers it to be a unit. probably it is because of kerns and boxes (and that would be true too of "\TeX book" which won't hyphenate either unless one tells it to with a control sequence definition). also, remember that i'm still working mostly within an ot1 environment. – barbara beeton Aug 22 '17 at 20:15