Had Judy been more careful on the mathematics exam, she ________ much better results now.
句意：如果朱迪在数学考试中更加小心，她现在可能会得到更好的结果。根据语法知识可知， 在与现在事实相反的虚拟语气中，主句用would/could/should+动词原形。故选D。