do you exercise Miss Lin?-Once a week. A. How longB. How oftenC. How farD. How soo

问题补充：

--- do you exercise, Miss Lin? ---Once a week.

A. How long

B. How often

C. How far

D. How soon

答案：

A. How long

(答案→)B. How often

C. How far

D. How soon

解析：疑问词辨析。How long多长；How often多久一次；How far多远；How soon多久。

根据答语内容为Once a week.可知上文提问频率，故选B。。