— do you have an Art Festival in your school?— Once a year.A. How longB. How oftenC. How

问题补充：

— do you have an Art Festival in your school?

— Once a year.

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：

根据答语once a year可知问的是频度，how often多久一次符合题意，故选B。how long问的是时间或物体的长度；how far问的是距离；how soon问还过多久，都不对。