问题补充：
– Do you know William failed the exam, Jenny?
-- ? As far as I know, he is always working hard.
A. So what
B. How come
C. Why not
D. What for
答案：
A. So what
(答案→)B. How come
C. Why not
D. What for
解析：考查交际用语。So what那又怎么样；How come怎么会那样；Why not为什么不；What for 为何。句意：你知道William考试失败了吗？怎么会那样，据我所知，他一直努力学习。所以选B。
