– do you visit your grandparents? –Twice a month. A. How long B. How soon C. How often

问题补充：

– do you visit your grandparents? –Twice a month.

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

答案：

解析：考查特殊疑问词。根据回答：一月两次，可知用how often 多久一次，选C。