var
Mytext,TempText:Textfile;
S:string[20];
i:integer;
begin
AssignFile(TempText:TempText.txt) //创建临时文件
Rewrite(TempText);
AssignFile(MyText,'MyText.text')
//关联需要改动的文件
Reset(MyText);
try
while not eof(myText) do
begin
ReanLn(myText,s,i);
s:='abcd'+s
//插入字段
Writeln(TempText,s,i);
end;
finally
closefile(Temptext);
closefile(MyText);
end;
end;