— do you surf the Internet Kate? — Not often twice a month.A. How long B. How oldC. How

问题补充：

— do you surf the Internet, Kate? — Not often, twice a month.

A. How long

B. How old

C. How often

D. How many times

答案：

A. How long

B. How old

(答案→)C. How often

D. How many times

解析：句意: -Kate，你多久上一次网？-不是经常上，一个月两次。根据Kate的回答twice a month 可知，这里是在询问她上网的频率，故应用how often。how long 多长时间，对一段时间提问；how old 多大，几岁，询问年龄；how many times 多少次，询问次数。故选C。