—Believe it or not, I have met him before.
—No kidding? you've never mentioned it?
A. What for
B. How e
C. How about
D. What if
网友回答
A. What for
(答案→)B. How e
C. How about
D. What if
解析：B考察交际用语；句义：—不关你信不信，我以前见过他。—真的吗？你怎么从来没有提过啊？A为何目的？Ｂ为什么？怎么会？C怎么样：D要是…又如何？根据句义说明B正确。