---does your mother watch the Talk show?-Once a week.A. How longB. How oftenC. How soon

问题补充：

---does your mother watch the Talk show? ---Once a week.

A. How long

B. How often

C. How soon

D. How many

答案：

A. How long

(答案→)B. How often

C. How soon

D. How many

解析：句意：你妈妈多久看一次脱口秀节目？一周一次。提问做某事的频率用how often；how long表示多久，多长时间；how soon表示多快，要过多久以后；how many表示多少，强调数量；根据下文Once a week，可知提问的是频率，故选B。