PL0书中程序 ...........\program4 ...........\........\PROGRAM4.PAS ...........\........\testin.pl0 ...........\program5 ...........\........\program5.pas ...........\........\testin.pl0 ...........\........\testin2.pl0 ...........\program6 ...........\........\program6.pas ...........\........\testin.pl0