— will your father be back?
—My father will be back in half an hour.
A. How long
B. How soon
C. How often
D. How far
网友回答
A. How long
(答案→)B. How soon
C. How often
D. How far
解析：根据题干中的will和答语，可知，应该用how soon“多久”，因为how soon用于将来时中；how long表示“多长时间”，不能用于将来时；how often是“多久一次”，是问频率；how far“多远”是问路程。所以本题选B。