—do you write to your parents?—Once a month.A. How muchB. How oftenC. How longD. How

问题补充：

—do you write to your parents?

—Once a month.

A. How much

B. How often

C. How long

D. How

答案：

A. How much

(答案→)B. How often

C. How long

D. How

解析：once a month表示一月一次，常用how often来提问。