Hi, Hans: When I used AdobeSongStd-Light as my main font and used LMRoman10-Regular as the fallback font, I found that the spaces between Chinese characters and English words are perfect, for example: \definefontfeature [zh][mode=node,script=hang,lang=zhs] \definefontsynonym [zhserif][name:AdobeSongStd-Light][features=zh] \definefontfallback [westernserif] [name:LMRoman10-Regular][0x0000-0x0400][force=yes] \definefontsynonym [song][zhserif][fallbacks=westernserif] \definefont[myfont][song at 12pt] \starttext \myfont 中文 English 之间的间隔\par 中文~English~之间的间隔\par 中文\;English\;之间的间隔 \stoptext But, when I used SimSun instead of AdobeSongStd-Light, the spaces between Chinese characters and English words became larger and ugly. In previous example, spaces in the first two lines of text are larger than those in the third one, even the spaces between English words also become larger. I remerbered what you said, the fallback fonts can be independent of the main font. However, I think the spaces between the words are releated to the main font. Would you give me a method for solving this problem? The pdf files used as comparison are attached to in the mail and you can do a comparative analysis. Thanks. by Li Yanrui