Car diagnosis program (both levels of the decision tree):

	program carb;

	var
		response: string;
	begin
	writeln('Was your car running just before this?');
	readln(response);
	if response = 'yes' then
		begin
		writeln('Fuel problems are likely.');
		writeln('Is gas gauge on empty?');
		readlin(response);
		if response = 'yes' then
			begin
			writeln('Get gas.');
			end
		else
			begin
			writeln('Call a tow truck.');
			end;
		end
	else
		begin
		writeln('Electrical problems seem likely.');
		writeln('Does engine crank?');
		readlin(response);
		if response = 'yes' then
			begin
			writeln('Check out gas.');
			end
		else
			begin
			writeln('Check out battery');
			end;
		end;
	readln;
	end.

Sample output:

>Was your car running just before this?
<no
>Electrical problems seem likely.
>Does engine crank?
<no
>Check out battery