—do you surf the Internet?—Once a week.A. HowB. How oldC. How oftenD. How many times

问题补充：

—do you surf the Internet?

—Once a week.

A. How

B. How old

C. How often

D. How many times

答案：

A. How

B. How old

(答案→)C. How often

D. How many times

解析：回答语是频率，对频率提问的用how often，故选C。A答案对方式提问，B答案

对年龄提问，D答案对次数提问，故都不能选。