—do you write to your parents?-- Twice a month.A. How oftenB. How manyC. How longD. How so

问题补充：

—do you write to your parents?

-- Twice a month.

A. How often

B. How many

C. How long

D. How soon

答案：

(答案→)A. How often

B. How many

C. How long

D. How soon

解析：句意：你多久给你的爸爸妈妈写一次信？一个月写两次。How many多少，与可数名词连用；How often 多久一次，How long多长时间，How soon多久，表将来。