Strange display language in gnome shell

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http://askubuntu.com – I logged in gnome-shell, and found that the display language is set to some strange Asian language (I think) without my prompt. I tried to change the locale settings but found that the default language is English (how?) despite of that strange language. Here's a snapshot, See the strange word instead of "Activity": I'm on Ubuntu 12.04 LTS. Output of locale: LANG=zh_CN.UTF-8 LANGUAGE=zh_CN:en_US:en LC_CTYPE="zh_CN.UTF-8" LC_NUMERIC=en_US.UTF-8 LC_TIME=en_US.UTF-8 LC_COLLATE="zh_CN.UTF-8" LC_MONETARY=en_US.UTF-8 LC_MESSAGES="zh_CN.UTF-8" LC_PAPER=en_US.UTF-8 LC_NAME=en_US.UTF-8 LC_ADDRES (HowTos)