makes this small restaurant different is that it offers three free cups of beer to its customers every Sunday morning．
A. Who
B. What
C. Whoever
D. Whatever
网友回答
A. Who
(答案→)B. What
C. Whoever
D. Whatever
解析：考查主语从句。主从 makes this small restaurant different缺少主语，指代免费提供啤酒这件事，所以选B。