— you were so late this morning?— forgot to set the alarm before going to bed last night.A

问题补充：

— you were so late this morning?

— forgot to set the alarm before going to bed last night.

A. Why

BHow come

CHow about

D. How

答案：

A. Why

(答案→)B. How come

C. How about

D. How

解析：考查疑问词的用法。“你今天上午为什么这么晚？”“昨晚睡前忘记设定闹钟了。”why和how后应该用疑问语序，how about后跟名词、代词、动名词；how about“为什么，怎么会......”，句子不用疑问语序。故选B。