— do you go to the gym? — Once a week.A. How farB. How oftenC. How longD. How soon

问题补充：

— do you go to the gym?

— Once a week.

A. How far

B. How often

C. How long

D. How soon

答案：

A. How far

(答案→)B. How often

C. How long

D. How soon

解析：How far多远；How often多久一次；How long多长；How soon多久。根据下文，每周一次。可知上文问的是，你多久去一次体育馆？故选B。