---do you surf the Internet?Once a week.A. How often B. How long C. How soonD. How man

问题补充：

---do you surf the Internet?

--- Once a week.

A. How often

B. How long

C. How soon

D. How many

答案：

(答案→)A. How often

B. How long

C. How soon

D. How many

解析：根据答语内容Once a week.可知答案为A。表示多久一次的 意思。