Sorry to have bothered you guys, I've solved my problem now. Thank you for
your kind helps.

-- 
Sincerely yours,
Chen
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          Zhi-chu Chen | Shanghai Synchrotron Radiation Facility
         No. 2019 | Jialuo Rd. | Jiading | Shanghai | P.R. China
             tel: 086 21 5955 3405 | zhichu.chen.googlepages.com
                                               | www.sinap.ac.cn
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