问题补充:
— did you stay in Hong Kong? — About 20 days.
A. How often
B. How soon
C. How long
D. How far
答案:
A. How often
B. How soon
(答案→)C. How long
D. How far
解析:句意:你在香港待了多长时间?——大约20天。A. How often多久一次,表示频率;B. How soon将要多久,表示将要多长时间;C. How long多长时间,对时间段提问;D. How far多远,对距离提问。根据About 20 days.可知这是对时间段提问,故用疑问词how long。故选C。