答案：D

题目分析：句意：如果我再年轻十岁，我会很高兴的。这里是对现在的虚拟，从句用过去式，主句也是对现在的虚拟，所以用would+动词原形，故选D。

点评：本题难度适中。虚拟语气是近几年高考的热点，虚拟语气的情况复杂，形式多样，需要考生牢记它们的不同的用法，再根据不同的语境分析句子应该用哪种情况的虚拟。考生误选C。

即学即练：If I had worked harder at school, I ________ in a comfortable office now.

A. would sit                     B. would have sat

C. would be sitting              D. were sitting

解析：C。句意：如果我上学时再努力一些的话，现在可能正坐在一间舒适的办公室里呢。