我遇到了以下问题：尝试在全希伯来语文档（即主要文档语言是希伯来语）中拥有枚举环境会导致Incomplete \iffalse。使用德语作为主要文档语言时，同样的方法可以正常工作。原因是什么？
% !TEX encoding = UTF-8 Unicode
% !TEX TS-program = xelatex
\documentclass[14pt,a4paper]{scrbook}
\usepackage[nouppercase,headsepline]{scrpage2}
\usepackage{fontspec}
%\usepackage{xltxtra}
\usepackage{polyglossia}
\setmainlanguage{hebrew}
\setotherlanguage{german}
%\setmainlanguage{german}
%\setotherlanguage{hebrew}
\newfontfamily{\germanfont}{Times New Roman}
\newfontfamily{\hebrewfont}{David CLM}
\begin{document}
טקסט
\begin{enumerate}
\item מבוא
\begin{enumerate}
\item מקור המובא
\item דוגמת אבי
\item המינוח מאת דיטריך בונהויפֿר
\end{enumerate}
\item התפתחות בכנסיה
\item חטא וסליחה
\item חזרה בתשובה ובשאלה
\end{enumerate}
טקסט
\end{document}
以希伯来语作为主要语言的运行会导致以下错误：
! Incomplete \iffalse; all text was ignored after line 28.
<inserted text>
\fi
<*> test_enum.tex
The file ended while I was skipping conditional text.
This kind of error happens when you say `\if...' and forget
the matching `\fi'. I've inserted a `\fi'; this might work.
! Emergency stop.
<*> test_enum.tex
*** (job aborted, no legal \end found)
\listfiles（以德语为主要语言，不会出错）结果为：
*File List*
scrbook.cls 2010/09/17 v3.07 KOMA-Script document class (book)
scrkbase.sty 2010/09/17 v3.07 KOMA-Script package (KOMA-Script-dependent bas
ics and keyval usage)
scrbase.sty 2010/09/17 v3.07 KOMA-Script package (KOMA-Script-independent b
asics and keyval usage)
keyval.sty 1999/03/16 v1.13 key=value parser (DPC)
scrlfile.sty 2009/03/25 v3.03 KOMA-Script package (loading files)
tocbasic.sty 2010/09/14 v3.06a KOMA-Script package (handling toc-files)
size14.clo 1999/11/11 v1.4a NON-Standard LaTeX file (size option)
typearea.sty 2010/09/17 v3.07 KOMA-Script package (type area)
scrpage2.sty 2010/04/22 v2.5 LaTeX2e KOMA-Script package
polyglossia.sty 2010/07/27 v1.2.0a Babel replacement for XeLaTeX
etoolbox.sty 2010/09/12 v2.0a e-TeX tools for LaTeX
etex.sty 1998/03/26 v2.0 eTeX basic definition package (PEB)
makecmds.sty 2009/09/03 v1.0a extra command making commands
fontspec.sty 2010/11/17 v2.1e Advanced font selection for XeLaTeX/LuaLaTeX
expl3.sty 2010/11/13 v2083 L3 Experimental code bundle wrapper
l3names.sty 2010/10/03 v2064 L3 Experimental Naming Scheme for TeX Primitiv
es
l3basics.sty 2010/10/03 v2063 L3 Experimental basic definitions
l3expan.sty 2010/09/20 v2037 L3 Experimental Argument Expansion module
l3tl.sty 2010/12/18 v2103 L3 Experimental Token Lists
l3int.sty 2010/10/17 v2077 L3 Experimental Integer module
l3quark.sty 2010/09/20 v2036 L3 Experimental Quark Commands
l3seq.sty 2010/03/29 v1879 L3 Experimental sequences and stacks
l3toks.sty 2010/09/20 v2037 L3 Experimental Token Registers
l3prg.sty 2010/10/03 v2063 L3 Experimental control structures
l3clist.sty 2010/10/09 v2071 L3 Experimental comma separated lists
l3token.sty 2010/10/03 v2063 L3 Experimental token investigation and manipu
lation
l3prop.sty 2010/11/23 v2087 L3 Experimental Property Lists
l3msg.sty 2010/10/02 v2052 L3 Experimental LaTeX Messages module
l3io.sty 2010/10/03 v2063 L3 Experimental i/o module
l3skip.sty 2010/11/23 v2088 L3 Experimental skip registers
l3box.sty 2010/09/26 v2048 L3 Experimental Box module
l3keyval.sty 2010/04/11 v1890 L3 Experimental keyval processing
l3keys.sty 2010/11/11 v2082 L3 Experimental key-value support
l3precom.sty 2010/02/09 v1793 L3 Experimental precompilation module
l3xref.sty 2010/02/09 v1786 L3 Experimental cross referencing
l3file.sty 2010/03/21 v1853 L3 Experimental file loading
l3fp.sty 2010/12/18 v2104 L3 Experimental floating-point operations
l3luatex.sty 2010/07/18 v1985 L3 Experimental LuaTeX functions
calc.sty 2007/08/22 v4.3 Infix arithmetic (KKT,FJ)
xparse.sty 2010/10/13 v2073 Generic document command parser
xkeyval.sty 2008/08/13 v2.6a package option processing (HA)
xkeyval.tex 2008/08/13 v2.6a key=value parser (HA)
fontspec-patches.sty 2010/11/17 v2.1e Advanced font selection for XeLaTeX/Lu
aLaTeX
fixltx2e.sty 2006/09/13 v1.1m fixes to LaTeX
fontenc.sty
eu1enc.def 2010/05/27 v0.1h Experimental Unicode font encodings
eu1lmr.fd 2009/10/30 v1.6 Font defs for Latin Modern
xunicode.sty 2010/11/06 v0.96 provides access to latin accents and many othe
r characters in Unicode lower plane
fontspec.cfg
gloss-german.ldf polyglossia: module for german
babelsh.def 2009/05/07 Babel common definitions for shorthands
Taken verbatim from babel.def (2008/07/06 v3.8l)
gloss-hebrew.ldf polyglossia: module for hebrew
bidi.sty 2010/09/28 v1.1.5a <commit 98> Bidirectional typesetting in pla
in TeX and LaTeX
iftex.sty 2010/07/25 v0.2 Provides if(tex) conditional for PDFTeX, XeTeX,
and LuaTeX
loadingorder-bidi.def 2010/07/25 v0.5 making sure that bidi is the last pack
age loaded
xetex-bidi.def 2010/08/01 v0.8 bidi adaptations for XeTeX engine
footnote-xetex-bidi.def 2010/07/25 v0.5 bidi footnote macros for XeTeX engin
e
scrbook-xetex-bidi.def 2010/07/25 v0.3 bidi adaptations for scrbook class fo
r XeTeX engine
hebrewcal.sty 2008/07/01 v2.4 Hebrew calendar for polyglossia (adapted from
hebcal.sty in Babel)
cal-util.def
babel-hebrewalph.def 2010/03/02 Babel definitions for Hebrew numerals
Adapted from hebrew.ldf (2005/03/30 v2.3h)
***********