const
  eps=0;
var
  b:array[1..10000] of extended;
  n,d,s1,e1,s2,e2:integer;
  l1,l2:extended;
  a:extended;
  i,f,back:integer;
  frontsearch,frontfound,backsearch,backfound:Boolean;
procedure SearchForFrontWall;
var
  i:integer;
begin
  i:=0;
  frontsearch:=false;
  frontfound:=false;
  repeat
    inc(i);
    frontsearch:=b[i]-35<=eps
  until (i=n) or frontsearch;
  if frontsearch then
    begin
      repeat
        inc(i);
        frontfound:=b[i]-95>=eps
      until (i=n) or frontfound;
      if frontfound then
        begin
          f:=i;
          writeln('Surface found at ',f,'.')
        end
    end
end;
procedure SearchForBackWall;
var
  i:integer;
begin
  i:=f;
  backsearch:=false;
  backfound:=false;
  repeat
    inc(i);
    backsearch:=b[i]-35<=eps
  until (i=n) or backsearch;
  if backsearch then
    begin
      if i<f+d-1 then
        i:=f+d-1;
      repeat
        inc(i);
        backfound:=b[i]-95>=eps
      until (i=n) or backfound
    end;
  if backfound then
    begin
      back:=i-f;
      writeln('Bottom found at ',back,'.')
    end
  else
    begin
      writeln('No bottom.');
      back:=n-f+1
    end;
end;
procedure SearchChannel(num,s,e:integer;l:extended);
var
  i,m:integer;
begin
  if s>=back then
    writeln('Channel ',num,': No search.')
  else
    begin
      m:=s;
      if e>=back then
        e:=back-1;
      for i:=s+1 to e do
        if b[i+f]-b[m+f]>eps then
          m:=i;
      if b[m+f]-l>eps then
        writeln('Channel ',num,': Object at ',m,'.')
      else
        writeln('Channel ',num,': No object.')
    end
end;
begin
  readln(n,d,s1,e1,l1,s2,e2,l2,a);
  for i:=1 to n do
    readln(b[i]);
  SearchForFrontWall;
  if frontfound then
    begin
      for i:=f+1 to n do
        b[i]:=b[i]*(1+(i-f)*a);
      SearchForBackWall;
      SearchChannel(1,s1,e1,l1);
      SearchChannel(2,s2,e2,l2)
    end
  else
    writeln('No surface.')
end.

8 0 3 6 72 7 7 22 0.008000
97
19
91
66
65
24
52
96

my AC program outputs:

Surface found at 8.
No bottom.
Channel 1: No search.
Channel 2: No search.

Thanks for the test, but I still can't turn it into AC: if I replace extended with either real or double I get WA #5. And my program evaluates your test case correctly after just one small fix for all those real types!

Can someone please help me?

If FRONT+D >N, you're in trouble because of "until(i=n)". I had same problem in my C++ solution, but it was WA5 :)