用stata10生成数据库时没有使用"saveold"，这样，低版本打不开。

使用 -use10- 命令可解决这个问题。

use10 from http://fmwww.bc.edu/RePEc/bocode/u
    'USE10': module to use and describe version 10 datafiles in Stata 9.2 /
    Use10 allows users of Stata 9 to load datasets created with Stata / 10. No
    additional software (converters) are required. Users can / easily modify
    the program to change the rules of how / transformation of formats is