一个vc程序，不通过控制面板，实现光驱、软驱USB等设备的禁用和恢复-a vc procedures, not through the control panel and realize drive, floppy drive and other USB equipment and the restoration of the ban

lear all A=wk1read( cigarette.wk1 ,1,0) W1=wk1read( Spat-Sym-US.wk1 ) Dataset downloaded from www.wiley.co.uk/baltagi/ Source: Baltagi and Levin (1992) and Baltagi, Griffin and Xiong (2000). Descr iption: Panel Data, 46 U.S. States