var s,s1:string; ff:textfile; begin if opendialog1.Execute then assignfile(ff,opendialog1.FileName); reset(ff); readln(ff,s,s1); showmessage(s); showmessage(s1); 我读取一个txt文档资料里后,为什么只显示第一行和最后一行的资料? 其实我想知道readln加了parameters之后的用法!

var
 s: string;
 ff: textfile;
begin
  if opendialog1.Execute then
  begin
    AssignFile(ff, OpenDialog1.FileName);
    Reset(ff);
    while not Eof(ff) do
    begin
      readln(ff, s);
      showmessage(s);
    end;
    CloseFile(ff);
  end;
end;