----does your sister surf the internet?-About once a week.A. How longB. How oftenC. Ho

问题补充：

----does your sister surf the internet?

---- About once a week.

A. How long

B. How often

C. How many

D. How soon

答案：

A. How long

(答案→)B. How often

C. How many

D. How soon

解析：本题回答语表示的是频率，对此提问用how often，故本题选B。