—are you staying there?—Just for two days. A. How long B. WhenC. How oftenD. How many

问题补充：

—are you staying there?

—Just for two days.

A. How long

B. When

C. How often

D. How many

答案：

(答案→)A. How long

B. When

C. How often

D. How many

解析：How long多长；When什么时候；How often多久一次；How many多少个。根据下文，只有两天。可知上文对时间长久进行提问。选A。