do you eat fast food?---Twice a week.A. How long B. How soon C. How often

问题补充：

--- do you eat fast food?

---Twice a week.

A. How long B. How soon C. How often

答案：

解析：

试题分析: How long 多长 How soon 多久 How often多久一次。根据答语，一周两次。可知上文问的是频度，故选C。