— do you go to the zoo with your brother?—Three times a month.A. How long B. How oftenC. H

问题补充：

— do you go to the zoo with your brother?

—Three times a month.

A. How long

B. How often

C. How old

D. How much

答案：

A. How long

(答案→)B. How often

C. How old

D. How much

解析：句意：--你和你的弟弟多长时间去一次动物园？--一个月三次。A. How long多长；B. How often多久一次；C. How old多大； D. How much多少。根据答语可知这里回答的是表示频率的词，根据句意故选B。