Chemformula 不显示箭头（不使用 dvips）

Question

我一直在尝试一个简单的反应，chemformula但它没有显示箭头。有一个类似的问题这里但该解决方案对我来说不起作用（我没有使用 dvips）。

这里有一个平均能量损失

\documentclass[a4paper,12pt]{article}
\usepackage[spanish]{babel}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{tikz}
\usetikzlibrary{arrows}
\usepackage{chemmacros}
\chemsetup{modules=all}
\chemsetup{formula=chemformula}


\begin{document}

\ch{glucosa_{(s)} <=> glucosa_{(aq)}}


\end{document}

报告的错误是：

*************************************************
* chemmacros warning: "no-greek"
* 
* You haven't loaded any package for upright Greek letters or no unique choice
* was possible. Either load one of packages specified in the manual or select
* a chemgreek mapping manually.
*************************************************

(/usr/local/texlive/2018/texmf-dist/tex/latex/elements/elements_names_spanish.d
ef)

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!
! chemformula error: "unknown-arrow"
! 
! The arrow type <=> doesn't exist on line 26.
! 
! See the chemformula documentation for further information.
! 
! Type <return> to continue.
!...............................................  

l.26 \ch{glucosa_{(s)} <=> glucosa_{(aq)}}

Answer 1

您必须删除babel的修改（正在进行>和<活动的修改）。

\documentclass[a4paper,12pt]{article}
\usepackage[spanish]{babel}
\usepackage{tikz}
\usetikzlibrary{arrows}
\usepackage{chemmacros}
\chemsetup{modules=all}
\chemsetup{formula=chemformula}

\let\chold\ch
\renewcommand\ch[1]{%
    \catcode`<=12
    \catcode`>=12
    \chold{#1}%
    \catcode`<=\active
    \catcode`>=\active
}

\begin{document}
<<Test>>

\ch{glucosa_{(s)} <=> glucosa_{(aq)}}

<<Test>>
\end{document}

---

替代方案（Troy 在评论中提到）：

\documentclass[a4paper,12pt]{article}
\usepackage[spanish,es-noquoting]{babel}
\usepackage{tikz}
\usetikzlibrary{arrows}
\usepackage{chemmacros}
\chemsetup{modules=all}
\chemsetup{formula=chemformula}

\begin{document}
<<Test>>

\ch{glucosa_{(s)} <=> glucosa_{(aq)}}

<<Test>>
\end{document}