---We could invite John and Barbara to the Friday night party.
--- Yes, ? I’ll give them a call right now.
A. what for
B. why not
C. why
D. what
网友回答
A. what for
(答案→)B. why not
C. why
D. what
解析：考查交际用语。A为了说明？B为什么不？C为什么？D什么？句意：—我们可以邀请John和Barbara来参加星期五的聚会。—是的。为什么不呢？我现在就给他们打电话。根据句意说明后者是同意前者的意见的。故B正确。