here is my code:
program p1601;
var
  a:array[1..10000]of char;
  i,j,k,n,m,l:longint;
begin
  while not eof(input) do
    begin
      fillchar(a,sizeof(a),' ');
      l:=0;
      while not eoln(input) do
        begin
          inc(l);
          read(a[l]);
        end;
      for i:=2 to l do
        if a[i] in['A'..'Z','a'..'z'] then
        if a[i-1] in ['.','!','?']
          then upcase(a[i])
          else
            if a[i] in['A'..'Z']
              then a[i]:=chr(ord(a[i])+32);
      for i:=1 to l do
        write(a[i]);
      writeln;
      readln;
    end;
end.

Could you give me some tests that tell me why I am wrong?
Thanks a lot!