请仔细阅读下列程序段:
PASCAL语言
var
a:array[1..3,1..4] of integer;
b:array[1..4,1..3] of integer;
x,y:integer;
begin
for x:=1 to 3 do
for y:=1 to 4 do
a[x,y]:=x-y;
for x:=4 downto 1 do
for y:=1 to 3 do
b[x,y]:=a[y,x];
writeln(b[3,2]);
end.
上列程序段的正确輸出是（ ）．