Please help

i try to [font=Arial][size=2]move an object around on the screen
[/size][/font][font=Arial][size=2]by using the arrow keys

and i did it but the problem is when i click two arrow keys
simultaneous the object moves only by on direction
if i clicked by example the up key and left key the object moves only to up or to the left
and i need to move the object inclined

[color=Red]please help[/color][/size][/font]