Question

4. (2013江苏大丰第四中学月考，16, ★★☆ )—       do you have this kind of match?

—Once a year.

   A. How long   B. How often

   C. How many   D. How much

Answer 1

4. B 

how long“多长”；how often “多长时间一'次” ；how many “多少”，后面接可数名词复数;how much “多少”，后面接不可数名词或询问价格。根据答语“Once a year."可知上文提问的是频率。故选B。