— do you go to see your grandparents?—Once a week.A. How farB. How longC. How oftenD. How

问题补充：

— do you go to see your grandparents?

—Once a week.

A. How far

B. How long

C. How often

D. How soon

答案：

A. How far

B. How long

(答案→)C. How often

D. How soon

解析：How far多远；How long多长；How often多久一次；How soon多久。根据下文，每周一次。可知上文问的是，你多久去看你爷爷奶奶一次？故选C。