edit1.clear;
edit1.text:=‘‘;
MaskEdit2.text:=‘‘;
memo1.lines.clear;
query2.close;
listbox2.items.clear;
radiogroup1.itemindex:=-1;
checkbox2.state:=cbunchecked;
combobox1.clear;
button1.enabled:=false;
原文：http://www.cnblogs.com/ddxxxb/p/6895344.html